8th Workshop

Ellipsometry March 10 - 12, 2014

Dresden, Germany

BOOK OF ABSTRACTS

IMPRINT Leibniz-Institut für Polymerforschung Dresden e. V. Hohe Straße 6 01069 Dresden, Germany Phone: +49 351 4658-282 Fax: +49 351 4658-214 E-Mail: wse2014@ipfdd.de Web: www.ipfdd.de Layout Kerstin Wustrack Juliane Jeschke Josi Bürger

INTRODUCTION It is our pleasure to welcome you to the 8th Workshop Ellipsometry. This event is initiated by the Arbeitskreis Ellipsometrie - Paul Drude e. V. and organised by the Leibniz-Institut für Polymerforschung Dresden e. V. (Leibniz Institute of Polymer Research Dresden) in the beautiful baroque city of Dresden. The conference carries on the tradition of successful meetings held since 2000 in Stuttgart, Berlin, Zweibrücken, and Leipzig and aims to bring together experts and students in the field of ellipsometry and related optical methods of metrology. This conference has been designed as a platform for new advances in the field, inspiration for discussion, interdisciplinarity, and novel developments in research and application. TOPICS • Magnetooptics, metamaterials, chiral structures, and photonic crystals • Rough and structured surfaces • Electronic properties and correlated systems • Organic and biological materials • Photovoltaics, microelectronics, metrology, and industrial applications • Latest news, hard- and software

CONFERENCE ORGANISATION Organising Institute Leibniz-Institut für Polymerforschung Dresden e. V. Organisation Committee: K.-J. Eichhorn (IPF Dresden), Chair P. Uhlmann (IPF Dresden) H. Schmidt (TU Chemnitz) E. Bittrich (IPF Dresden) K. Wustrack (IPF Dresden) M. Vinnichenko (IKTS Dresden) Program Committee: H. Schmidt (TU Chemnitz) E. Bittrich (IPF Dresden) R. Goldhahn (University Magdeburg) B. Gompf (University Stuttgart) A. Hertwig (BAM Berlin) K. Hinrichs (ISAS Berlin) P. Pokrowsky (FH Zweibrücken) R. Schmidt-Grund (University Leipzig)

International Advisory Board: H. Arwin (University Linköping, Sweden) U. Beck (BAM, Berlin, Germany) Ch. Bernhard (University Fribourg, Switzerland) Ch. Cobet (University Linz, Austria) B. Drevillon (LPICM, Palaiseau, France) J. Humlíček (University Masaryk, Brno, Czech Rep.) S. Logothetidis (University Thessaloniki, Greece) M. Losurdo (IMIP-CNR, Bari, Italy) P. Petrik (MTA-MFA, Budapest, Hungary) K. Postava (TU Ostrava, Czech Rep.) M. Schubert (University Nebraska-Lincoln, USA) H. Wormeester (University Twente, NL)

EXHIBITORS/SPONSORS

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ARBEITSKREIS ELLIPSOMETRIE – PAUL DRUDE E. V. In 1999 a group of German ellipsometry enthusiasts established the “Arbeitskreis Ellipsometrie” (German Association of Ellipsometry) with the aim of promoting ellipsometry in Germany. It was agreed to organise regular workshops to gather all ellipsometry protragonists: scientists, engineers, manufacturers, and students. The non-profit association Arbeitskreis Ellipsometrie (AKE) - Paul Drude e.V. was established in 2006. The AKE PD e. V. supports the scientific and technical understanding of optical metrology, in particular of ellipsometry. It provides a platform for the dissemination of new scientific results and experience, and promotes young people working in the field. Main activities:

• Organisation of the European Workshop Ellipsometry • Paul Drude Medal • Ellipsometry Database • Scientific Networking

Current Executive Board Prof. Dr. Peter Pokrowsky (FH Kaiserslautern/Zweibrücken), Chair Dr. Rüdiger Schmidt-Grund (Universität Leipzig) Dr. Karsten Hinrichs (ISAS, Berlin) Dr. Klaus-Jochen Eichhorn (IPF, Dresden) Dr. Andreas Hertwig (BAM, Berlin) Dr. Heidemarie Schmidt (Technische Universität Chemnitz)

Arbeitskreis Ellipsometrie (AKE) – Paul Drude e. V. c/o BAM, FG VI. 4 12205 Berlin http://www.ake-pdv.de E-Mail: vorstand@ake-pdv.org

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GENERAL INFORMATION This Book of Abstracts is your guide for the “8th Workshop Ellipsometry” and is your point of reference for the exciting program, overviews, general information, and the abstracts of all presentations and posters. Presentations abstracts are printed in the order they are presented. Poster abstracts have been arranged in the sequence of the topics. VENUE Dreikönigskirche – Haus der Kirche Hauptstraße 23 01097 Dresden Please find a map of Dresden and the conference venue on the next page. CONFERENCE OFFICE Opening hours MON 8:00 – 21:00 TUE 8:00 – 18:30 WED 8:00 – 13:30 Please contact a technical assistant in the plenary hall to upload your files in a timely manner prior to your presentation. CONTACT DETAILS OF THE ORGANISING INSTITUTION Leibniz-Institut für Polymerforschung Dresden e. V Hohe Straße 6, 01069 Dresden Phone: +49 351 4658 282 Email: wse2014@ipfdd.de Web: www.ipdff.de/wse2014 POSTERS All posters will be displayed for the whole duration of the conference. Poster presentations have been split between the two days according to the number assigned to your poster. Please make yourself available for the respective session. Poster sessions are scheduled for MON 18:00 - 21:00 ODD NUMBERS TUES 17:00 - 18:30 EVEN NUMBERS An award will be given to the best poster presentation. COFFEE & LUNCH BREAKS Coffee and snacks are provided outside the plenary hall (second floor), and in the dining hall and registration foyer (first floor). The lunch buffet will be served in the dining hall.

INTERNET For your convenience, free WiFi access is available throughout the conference venue. Please log in with the following details: Wifi configuration: DKK-WLAN Password: DKK2014HDK CONFERENCE DINNER The conference dinner will take place on Tuesday evening (March 11), at Feldschlösschen Stammhaus, a rustic restaurant and brewery. The informal buffet dinner will be complemented by drinks and music performed by the Jazz-Combo of the TU BigBand. The restaurant is located at Budapester Straße 32, 01069 Dresden. From the conference venue, you can reach the restaurant by tram from the station "Albertplatz", taking tram 7 (direction Pennrich) to the station "Budapester Straße" (from there upstairs). The journey takes approximately 12 minutes. Doors open at 19:00 and the buffet will be opened at 19:30. Please plan your arrival accordingly. PAUL DRUDE MEDAL The medal is awarded to a young, exceptional scientist for outstanding contributions to the field of ellipsometry metrology or spectroscopy. It was presented for the first time by the “Arbeitskreis Ellipsometrie – Paul Drude e. V.” in 2009 in Zweibrücken and has become an integral part of the Workshop. The medal as well as the poster award will be presented at the closing ceremony. WED 12:35 - 13:00 EXHIBITION Several manufacturers will showcase state-of-the-art devices in the dining hall. Accurion - Horiba - LOT - Semilab - Sentech (cf. page 1)

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MAP OF CONFERENCE LOCATION

Dreikönigskirche conference venue

Feldschlösschen restaurant

IPF Dresden

SCHEDULE status: as of Feb. 20, 2014

08:00 - 09:15

09:15 - 09:30 Opening

09:30 - 10:55 Rough and structured surfaces - RS1Chair: K.-J. Eichhorn

09:30 - 09:55 R. Brunner, Artificial anti-reflecting moth-eye structures 1909:55 - 10:15 A. Heinrich et al., Mueller matrix spectroscopic ellipsometry for photomask

evaluation20

10:15 - 10:35 Y. Battie et al., Investigation of the first step nucleation of two dimensional gold nanoisland anisotropic films by spectroscopic ellipsometry

21

10:35 - 10:55 M. König et al., Combinatorial QCM-D/GE-study of swelling and protein adsorption of polymer brushes grafted onto nanostructured surfaces

22

10:55 - 11:15 Coffee break

11:15 - 12:40 Electronic properties and correlated systems - EP1Chair: H. Schmidt

11:15 - 11:40 A. Sirenko, Investigation of electromagnetic modes in multiferroic oxides by far infrared Mueller-Matrix ellipsometry

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11:40 - 12:00 A. Charnukha et al., Spin-density-wave-induced anomalies in the optical conductivity of AFe2As2, (A=Ca, Sr, Ba) single-crystalline iron pnictides

24

12:00 - 12:20 A. Dubroka et al., Optical response of the topological insulator Bi2(TexSe1-x)3 thin films grown epitaxially on BaF2 substrates

25

12:20 - 12:40 C. Xu et al., Oblique incidence reflectance difference spectroscopy (OIRD) for real-time optical observation of the formation of the conducting interface between LaAlO3 and SrTiO3

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12:40 - 14:00 Lunch break

14:00 - 15:45 Photovoltaics, microelectronics, metrology, and industrial applications - PM1Chair: U. Beck

14:00 - 14:25 M. Foldyna, Optical characterization and modeling of nanostructures for photovoltaic applications

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14:25 - 14:45 M. Junige et al., Progress in spectroscopic ellipsometry for the in-situ real-time investigation of atomic layer depositions

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14:45 - 15:05 L. P. Selvaraj et al., BiFeO3-coated photocapacitive MIS diodes with added nonvolatile functionality

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15:05 - 15:25 D. V. Likhachev, Characterization of multi-layer ILD stack by spectroscopic ellipsometry in nanoelectronic manufacturing

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15:25 - 15:45 F. Bencheikh et al., Optical transitions of pi-conjugated organic materials for solar cells determined by spectroscopic ellipsometry

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15:45 - 16:05 Coffee break

16:05 - 17:45 Electronic properties and correlated systems - EP2Chair: P. Pokrowsky

16:05 - 16:25 P. Marsik et al., Low-energy interband transitions in the infrared response of pnictide superconductors

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16:25 - 16:45 D. Pröpper et al., Fano resonances in the infrared spectra of phonons in hyper-kagome Na_3Ir_3O_8

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Monday, March 10

Registration Page

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SCHEDULE status: as of Feb. 20, 2014

16:45 - 17:05 A. Erbe et al., Probing interfacial properties at metal/electrolyte interfaces of reactive materials: Examples from zinc and copper

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17:05 - 17:25 J. Klamser et al., Generalized ellipsometry of semipolar AlGaN 3517:25 - 17:45 K. Postava et al., Mueller matrix ellipsometry of monoclinic

Cu(H2O)2(C2H8N2)SO4 crystal36

17:45 - 18:00 Coffee break

18:00 - 21:00 Posters, Exhibition, and BeerChair: K.-J. Eichhorn

20:00 - 20:30 Evening lecture: B. Gompf, Was the sky always blue? The role of circular polarized light in the evolution of life

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08:30 - 09:55 Rough and structured surfaces - RS2Chair: H. Arwin

08:30 - 09:15 J. Bischoff, Ellipsometry-scatterometry theory: RCWA, C-method and the grating solver unigit

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09:15 - 09:35 M. Canepa et al., Interaction of proteins with nanoporous titania substrates 39

09:35 - 09:55 U. Beck et al., Imaging of surface impurities, imperfections, residues, contaminations and nano-scaled pattern: Microscopic techniques vs. ellipsometry

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09:55 - 10:15 Coffee break

10:15 - 11:20 Organic and biological materials - OBM1Chair: E. Bittrich

10:15 - 10:40 J. Rappich, In-situ IR-ellipsometry applied to organic/silicon interfaces in solution

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10:40 - 11:00 S. Rauch et al., In situ spectroscopic ellipsometry - a tool to study 'grafting-on-top' processes in reactive polymer brush systems

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11:00 - 11:20 W. Ogieglo et al., In-situ ellipsometry studies of thin swollen polymer films, a review

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11:20 - 11:40 Coffee break

11:40 - 12:45 Organic and biological materials - OBM2Chair: K. Hinrichs

11:40 - 12:05 L. Sun, Reflectance difference spectroscopy: A versatile tool for surface science 44

12:05 - 12:25 J. Gasiorowski et al., Ellipsometric spectroelectrochemistry - an insight in the optical properties of doped organic semiconductors

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12:25 - 12:45 A. Furchner et al., Humidity effects on functional polymer films 46

12:45 - 14:00 Lunch break

14:00 - 15:00 Rough and structured surfaces - RS3Chair: R. Goldhahn

14:00 - 14:20 V. Darakchieva et al., Phonon mode behavior and free-charge carrier parameters in high-Al content AlGaN determined by IR spectroscopic ellipsometry and optical hall effect

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14:20 - 14:40 F. Scholze et al., Polarization resolved measurements with the new EUVellipsometer of PTB

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Tuesday, March 11

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SCHEDULE status: as of Feb. 20, 2014

14:40 - 15:00 Ch. Cobet et al., Probing of the Cu(110) surface in electrolyte by in-situ spectroscopic ellipsometry, RAS and STM

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15:00 - 15:20 Coffee break

15:20 - 16:45 Rough and structured surfaces - RS4Chair: H. Wormeester

15:20 - 15:45 M. Schubert, From QCMD-ellipsometry combination to bire-fringence imaging chromatography and bire-fringence microscopy using sculptured co-lumnar thin films

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15:45 - 16:05 N. Kumar et al., Ellipsometric evaluation of unintentional surface layers and its influence on grating reconstruction in coherent Fourier scatterometry

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16:05 - 16:25 F. Bisio et al., Deep ultraviolet plasmonics in aluminum nanoparticle arrays 52

16:25 - 16:45 D. Rosu et al., Optical characterization of highly inhomogeneous thin films 53

16:45 - 17:00 Coffee break

17:00 - 18:30 Posters and Exhibition

19:00 Conference Dinner in the "Feldschlösschen Stammhaus", a rustic restaurant and brewery

08:30 - 10:20 Magnetooptics, metamaterials, chiral structures, and photonic crystals - MM1Chair: M. Schubert

08:30 - 09:15 T. Oates, Polarized spectroscopy of metal nanoparticle films and metamaterials

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09:15 - 09:40 K. Järrendahl, Polarizing natural chiral nanostructures 5509:40 - 10:00 V. Zviagin et al., Ellipsometric study of ZnFe2O4, CoFe2O4, and ZnCo2O4

spinel oxides56

10:00 - 10:20 A. Berrier et al., Mueller matrix characterization of plasmonic meanders 57

10:20 - 10:50 Coffee break

10:50 - 12:35 Photovoltaics, microelectronics, metrology, and industrial applications - PM2Chair: Ch. Cobet

10:50 - 11:15 M. Fried, Expanded beam spectroscopic ellipsometry for thin film solar cell production

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11:15 - 11:35 O. D. Gordan et al., In line monitoring of polycrystalline silicon formation by spray coating and flash lamp annealing of silicon nanoparticle suspensions

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11:35 - 11:55 A. Laskarakis et al., Optical properties and quality of roll-to-roll printed nanolayers for organic photovoltaics by in-line spectroscopic ellipsometry

60

11:55 - 12:15 P. Petrik et al., Fourier ellipsometry - an ellipsometric approach to fourier scatterometry

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12:15 - 12:35 P.-E. Hansen et al., Setting up a metrological traceable Mueller polarimeter 62

12:35 - 13:00 Awards, Concluding remarks

14:30 - 16:00 Mitgliederversammlung des AKE - Paul Drude e. V. (assembly of Paul Drude association)

Wednesday, March 12

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List of posters status: as of February 20, 2014

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1 Characterization of anisotropic plasmonic nanostructures from template-assisted self-assembly

Christian Kuttner, C. Hanske, M. Tebbe, A. Fery

2 Spectroscopic ellipsometry for characterization of graphene oxide on wafer surfaces

Alice Kasjanow, W. M. Munief, S. Ingebrandt, P. Pokrowsky

3 Fast vector magneto-optical generalized ellipsometry N. Du, Laveen Prabhu Selvaraj, R. K. Singh, R. Mattheis, I. Skorupa, O. G. Schmidt, H. Schmidt

4 Spectroscopic ellipsometry of highly ordered pyrolytic graphite in the far infrared wavelength regime

Till Mohr, W. Elsäßer

5 Wide spectral range ellipsometric study of nanostructured ITO/Ag hybrid layers by node spline method

Peter Basa, L. Makai, A. A. Khosroabadi, P. Gangopadhyay, R. A. Norwood

6 Magneto-optical characterization of organic/inorganic heterostructures with sub-millimeter resolution

Peter Richter, S. Banerjee, C. Schulze, D. Reuter, K. Hiller, M. Albrecht, D. R. T. Zahn, G. Salvan

7 Polarization of light reflected from Cetoniinae and Rutelinae beetles under various illuminations

Lia Fernández del Río, H. Arwin, K. Järrendahl

8 Mueller matrix characterization of three-dimensional gold nanostructures

E. Mbekwe Pafong, Audrey Berrier, B. Gompf, B. Frank, H. Giessen, M. Dressel

9 Optical and magnetooptical properties of magnetoplasmonic structured studied by Mueller matrix ellipsometry

Lukáš Halagačka, K. Postava, B. Dagens, F. Vaurette, J. M. Vanvolleghem, J. Ben Youssef, J. Pištora

10 Time-resolved ellipsometry studies of exciton-polaritons in a ZnO-based planar microcavity under pulsed excitation

Steffen Richter, C. Sturm, H. Franke, R. Schmidt-Grund, M. Grundmann

11 Characterization of nanoparticles at interfaces by imaging ellipsometry and Brewster angle microscopy

Peter H. Thiesen, C. Röling

12 Evaluation of vertical inhomogeneity in chemically etched porous silicon layers with VUV-NIR and FTIR ellipsometry

E. Agocs, B. Fodor, G. Gautier, F. Cayrel, Peter Petrik, P. Basa, L. Makai, D. Alquier, M. Fried

13 Determination of optical parameters and electrical conductivity of transparent conducting oxides by spectroscopic ellipsometry

Chaman Singh, S. Rath

14 Mueller-matrix-ellipsometry on blazed gratings produced by reactive ion beam etching

C. Bundesmann, R. Fechner, M. Burkhardt, M. Helgert, A. Gatto, F. Frost

15 Solvent - non-solvent mixture induced wrinkling in thin polymer films

Naval Singh, M. Kulkarni, P. Sachan, A. Sharma

16 From insulator to conductor: Infrared reflectivity of inverted fishnet designs

Stefano De Zuani, M. Rommel, H. Kumric, A. Berrier, J. Weis, B. Gompf, M. Dressel

17 Metallic nanoparticles under mild heating - real-time monitoring by spectroscopic ellipsometry

Jaroslav Kousal, O. Kylián, J. Hanuš, J. Čechvala, T. Steinhartová, J. Prokeš, H. Biederman

18 Mueller matrix ellipsometric investigations on strongly scattering granular films

K. Junge, Bruno Gompf, A. Berrier, M. Dressel

19 Impact of water droplets on a superhydrophobic, nanostructured surface in the presence of an external electric field

Georg M. Widholz, E. Förster, W. Mönch, W. Chen, J.-H. Dirks, J. Spatz, R. Brunner

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List of posters status: as of February 20, 2014

20 Combination of scalar diffraction theory and Rayleigh-Rice theory in spectroscopic ellipsometry of randomly rough surfaces: Application to boundaries of epitaxial ZnTe films

Ivan Ohlídal, D. Nečas, D. Franta

21 Optical and microstructural properties of the Au granular layers

Łukas Skowroński, A. Stachowicz, M. K. Naparty, A. A. Wronkowska

22 Rigorous simulations and analysis of the optical esponse of silica sculptured thin films

Lennart Fricke, C. Grüner, C. Bundesmann, R. Schmidt-Grund, M. Grundmann

23 A simple Fourier-Modal-Method solution for thin films with slanted structures

Lennart Fricke, R. Schmidt-Grund, M. Grundmann

24 Adapting a commercial microscope for studying nano-textured surfaces

Morten Hannibal Madsen and P.-E. Hansen

25 Determination of the plasmonic resonance of gold dot microarrays by imaging ellipsometry

Ovidiu D. Gordan, A. G. Milekhin, E. E. Rodyakina, C. Röling, A. V. Latyshev, D. R. T. Zahn

26 Mueller matrix decomposition of depolarizing metallic samples

Maria de Lourdes Miranda-Medina and K. Hingerl

27 Improve the performance of focused beam ellipsometer by using inter-layer crosstalk modeling

Attila Sütő and Z. Kárpáti

28 Ellipsometry study of the local surface plasmon resonance in silver nanostructures as a function of temperature

S. Nikipar, S. Moras, O. Gordan, D. R. T. Zahn

29 Optical features of FeTe(1-x)Se(x) superconductors probed by spectroscopic ellipsometry

Krzysztof Dorywalski, D. J. Gawryluk, R. Schmidt-Grund, L. Fricke, M. Grundmann, M. Berkowski, M. Piasecki

30 Optical probe of ferroelectric order in bulk and thin-film perovskite titanates

Matthias Rössle, C. N. Wang, P. Marsik, M. Yaydi-Rizi, K. W. Kim, A. Dubroka, I. Marozau, C. W. Schneider, J. Humlicek, D. Baeriswyl, C. Bernhard

31 Optical properties of gadolinium-iron garnet by spectroscopic ellipsometry

M. S. Diware, J. Choi, Han Gyeol Park, Y. Kang, Y. D. Kim, C. B. Park, K. Shin, K. H. Kim

32 Investigation of diamond-like carbon structure using a combination of synchrotron and conventional ellipsometry and spectrophotometry

David Nečas, D. Franta, P. Ondračka, L. Zajíčková, M. G. Mureşan, V. Peřina, R. Mikšová

33 Infrared ellipsometry study of the free charge carriers at the LAO/STO (110) and (111) interfaces

Megdad Yazdi-Rizi, M. Rössle, C. N. Wang, P. Marsik, C. Bernhard, G. Herranz

34 Effect of a Ge underlayer on the MIR-Vis-UV optical response of Ag thin films

Aleksandra A. Wronkowska, A. Wronkowski, M. Trzcinski, P. Wróbel, T. Stefaniuk, T. Szoplik

35 Percolation behavior of vanadium dioxide thin film during phase transition

Jean-Christophe Orlianges, R. Zaabi, C. Champeaux, A. Crunteanu

36 Approaches to calculate dielectric function of very thin carbon layers from spectroscopic ellipsometric measurements

Zsuzsanna Pápa, J. Budai, J. Csontos, Z. Toth

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List of posters status: as of February 20, 2014

37 Ellipsometric investigation of Cd(1-x)Hg(x)Te alloy colloidal quantum dot films

M. Isabel Alonso, M. Garriga, M. Campoy-Quiles, A. R. Goñi, F. Hetsch, S. V. Kershaw, A. L. Rogach, A. Bejaoui, C. H. To, Y. Foo, J. A. Zapien

38 Modeling of dielectric response of hafnia films Daniel Franta, D. Nečas, I. Ohlídal

39 Surface layers of ZnMgRE quasicrystals Saulius Tumėnas, V. Karpus, R. Kondrotas, A. Eikevičius, S. Paurazaitė, H. Arwin

40 Anisotropic dielectric function and effective electron masses of rutile SnO2

Rüdiger Goldhahn, C. Lidig, K. Lange, M. Neumann, N. Esser, M. E. White, M.-Y. Tsai, O. Bierwagen, J. S. Speck, M. Feneberg

41 Ellipsometric study of relaxor ferroelectric PbSc0.5Nb0.5O3 films

Dagmar Chvostova, T. Kocourek, M. Jelinek, A. Dejneka, M. Tyunina

42 Optical properties of nanofilms of wide bandgap BaTiO3 Ekaterina Chernova, D. Chvostova, T. Kocourek, M. Jelinek, V. Trepakov, A. Dejneka, M. Tyunina

43 Optical properties of HfO2 analysed using first principle calculations

Pavel Ondračka, D. Holec, D. Franta, M. Eliác, L. Zajíčková

44 Compositional induced changes in optical response of Si-doped titanium dioxide

Pavel Ondračka, D. Holec, D. Franta, E. Kedroňová, S. Elisabeth, A. Goullet, L. Zajíčková

45 Fast in-situ null ellipsometry for studying laser excited solid state surfaces

Zsolt Toth, Z. Pápa, J. Budai, A. Gárdián, J. Csontos, M. Füle

46 Optical properties of niobium-doped TiO2-x - a comparison of spectroscopic ellipsometry and spectrophotometry

Johanna Reck, S. Seeger, M. Weise, R. Mientus

47 Identification of scattering mechanisms in MOCVD-grown AlGaN/GaN high electron-mobility transistors by temperature-dependent THz optical Hall-effect and comparison with mobility calculations

St. Schöche, V. Darakchieva, P. Kühne, J.-T. Chen, U. Forsberg, E. Janzén, N. Ben Sedrine, C. M. Herzinger, J. A. Woollam, Mathias Schubert, T. Hofmann

48 In-situ infrared spectroscopic ellipsometry on temperature-responsive copolymer brushes

Annika Kroning, A. Furchner, M. Seeber, I. Luzinov, K. Hinrichs

49 Anomalous optical behavior of metal-polymer nanocomposites

Corentin Guyot, M. Voué

50 Swellipsometry in Twente: Measuring polymer swelling by in-situ ellipsometry

Wojciech Ogieglo, E. J. Kappert, M. Raaijmakers, H. Wormeester, M. Wessling, N. E. Benes

51 Optical properties of human dental enamel - an application of spectroscopic imaging ellipsometry

A. Kiesow, C. Röling, Peter H. Thiesen

52 Spectroscopic ellipsometry of self assembled monolayers: interface effects. The case of phenyl selenide SAMs on gold

Maurizio Canepa, G. Maidecchi, C. Toccafondi, O. Cavalleri, M. Prato, V. Chaudhari, V. A. Esaulov

53 Properties of the dielectric tensor of α-3,4,9,10-perylene tetracarboxylic dianhydride in the optical spectral range

M. Isabel Alonso, M. Garriga, J. O. Ossó, F. Schreiber, R. Scholz

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List of posters status: as of February 20, 2014

54 Specific and aspecific bonding of proteins on NTA self assembly monolayer on gold studied by spectroscopic ellipsometry

Ilaria Solano, F. Gramazio, L. Ianeselli, P. Parisse, O. Cavalleri, M. Castronovo, L. Casalis, M. Canepa

55 Real-time detection of antigen-antibody interaction using total internal reflection ellipsometry

Yu Ri Kang, J. S. Byun, J. C. Park, J. Choi, Y. D. Kim

56 Study on the collapsed arachidic acid with various compression rates by in-situ imaging ellipsometry

Han Gyeol Park, S. Y. Hwang,T. J. Kim, J. Y. Kim, N. S. Barange, J. C. Park, Y. D. Kim

57 Spectroscopic ellipsometry characterization of plasmonic films for surface-enhanced sensors

D. Gkogkou , I. M. Weidinger, P. Hildebrandt, K. Hinrichs, N. Esser, T. W. H. Oates

58 SPR enhanced dynamic spectroscopic ellipsometry for study of monomeric and dimeric granulocyte colony stimulating factor interaction with receptor

Z. Balevicius, Saulius Tumėnas, L. Tamosaitis, I. Baleviciute, A. Stirke, A. Makaraviciute, A. Ramanaviciene, A. Ramanavicius

59 In situ temperature-dependent spectroscopic ellipsometry of conjugated semiconducting materials

Lukas Bernhauser, E. D. Głowacki, C. Cobet, M. Scharber, K. Hingerl, N. S. Sariciftci

60 Biofunctionalization of polymer brushes with RGD peptides: An ellipsometric study

Evmorfia Psarra, U. König, K.-J. Eichorn, M. Stamm, P. Uhlmann

61 Swelling behavior of thermoresponsive polymer brush systems based on poly(2-oxazoline)s

Stefan Adam, K.-J. Eichhorn, J. C. Rueda, M. Stamm, M. Schubert, P. Uhlmann

62 Molecular orientation in light absorbing thin films for organic solar cells: Correlation of theory and experiment

O. Guskova, C. Schünemann, Eva Bittrich, K.-J. Eichhorn, K. Walzer, M. Levichkova, S. Grundmann, M. Stamm, J.-U. Sommer

63 Regression sum decomposition of Mueller matrices from depolarizing biological chiral reflectors

Roger Magnusson, R. Ossikovski, E. Garcia-Caurel, K. Järrendahl, H. Arwin

64 Electrical and optical properties of Ag films grown by ion beam sputter deposition

Carsten Bundesmann, R. Feder, H. Neumann

65 Temperature-controlled characterization of various materials by spectroscopic ellipsometry

Christophe Licitra, Y. Doudaine, L. Vignoud, F. Piegas Luce, F. Mazen, J. Tillier, E. Beche, P. Noé

66 Gas sensors using the SPR-effect detected byellipsometry

Daniel Fischer, A. Nooke, A. Hertwig, M. Weise, U. Beck, M. Kormunda

67 New applications of spectroscopic imaging ellipsometry in the field of organic photovoltaic (OPV) materials

Ch. Röling, Peter H. Thiesen, L. Toppare

68 Optical characterization of polymeric thin films for photovoltaic applications by ellipsometry

Veronika Schmiedova, P. Heinrichova, O. Zmeskal, M. Weiter

69 Real time monitoring of ALD Adrian Blümich, H. Gargouri, G. Dittmar, U. Richter, B. Gruska

70 Ellipsometric analysis of graphene layers from DUV to MIR

Sven Peters, B. Gruska

71 Characterisation of rutile TiO2 layers for high precision optical application

Thomas Modes, W. Schönberger

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List of posters status: as of February 20, 2014

72 Optical and nuclear studies of MOS structures Witold Rzodkiewicz, M. Kulik, J. Zuk, A. Panas, A. P. Kobzev

73 In-situ monitoring of electrical properties of ultrathin silver films by means of spectral ellipsometry

Jiri Bulir, M. Novotny, J. Lancok, J. Tomko, L. Fekete

74 Interference colors of TiO2/Ti/Glass systems deposited by magnetron sputtering

Łukasz Skowroński, M. Trzcinski, A. Antończak, M. Kustra, P. Domanowski, W. Wachowiak, D. Bratz, M. K. Naparty, T. Hiller, A. Bukaluk, A. A. Wronkowska

75 Optical and microstructural properties of TiO2 layers deposited on float glass by magnetron sputtering

Łukasz Skowroński, M. Trzcinski, M. Kustra, P. Domanowski, W. Wachowiak, M. K. Naparty, T. Hiller, A. Bukaluk, A. A. Wronkowska

76 YMnO3-based photocapacitive detectors in the visible light regime

Om Shandilya Choudhary, A. Bogusz, L. Selvaraj, V. John, D. Bürger, I. Skorupa, A. Lawerenz, K. Ettrich, O. G. Schmidt, H. Schmidt

77 Optical properties of graphene determined by spectroscopic ellipsometry, reflectometry and transmission photometry

Claus Villringer, J. Bauer, H. Lux, S. Schrader, F. De Matteis, M. Casalboni, O. Fursenko, G. Lippert, G. Lupina, J. Kitzmann

78 A fast line-ellipsometer Ferdinand Bammer, B. Ullmann, D. Hönig, P. Collins, T. Kehoe

79 Ellipsometric infrared microscopy Karsten Hinrichs, A. Furchner, J. Rappich, K.-J. Eichhorn, T. W. H. Oates

80 Tellipsometry in Twente: dynamics of thin film membranes under applied temperature profiles

Emiel J. Kappert, W. Ogieglo, M. Raaijmakers, B. Koziara, H. Wormeester, N. E. Benes

81 Time-resolved ellipsometric characterization of (Fe/Si)n multilayer film synthesis

Ivan Anatol'evich Tarasov, S. N. Varnakov, I. A. Yakovlev, S. M. Zharkov, N. N. Kosyrev, S. G. Ovchinnikov

82 Optical dimensional characterization of disordered silicon nanowire arrays for PV applications

Johannes Endres, M. Foldyna, G. Dai, S. Misra, P. Roca i Cabarrocas, A. Diener, B. Bodermann

83 Speeding-up imaging ellipsometry data cubes processing: a multivariate approach

C. Guyot, D. Hönig, P. Thiesen, Michel Voué

84 Specific modifications to enhance sensitivity in Null-ellipsometry

Marco Muth, R. P. Schmid, K. Schnitzlein

85 Real-time spectroscopic off-null ellipsometry N. Reineking, Dirk Hönig

86 Spectroscopic imaging ellipsometry in UV range St. Schneider, Dirk Hönig

87 Advanced dual rotating-compensator Mueller matrix polarimeter in transmission configuration for characterization of polarization elements in the visible spectral range

J. Kapitán, Vadim Evseev

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Abstracts of the talks

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ARTIFICIAL ANTI-REFLECTING MOTH-EYE STRUCTURES Robert Brunner1, Erik Förster1, Wenwen Chen2, Jan-Henning Dirks2, Joachim Spatz2

1 University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany 2 Max Planck Institute for Intelligent Systems, New Materials and Biosystems, Heisenbergstr. 3,

70569 Stuttgart, Germany Robert.Brunner@fh-jena.de Optical instruments play an essential part in many areas of technical appliances in the modern life. The broad diversity ranges e.g. from miniature cameras in mobile phones, to endoscopic medical devices to high performance lasers systems for material processing and lithography tools for semiconductor manufacturing industry. Regardless of the application, the quality of all optical instruments is strongly affected by potential reflection losses so that in general all optical elements have to be equipped with anti-reflective (AR) interfaces. Today, most frequently used antireflection (AR) coatings are based on multilayer interference structures. These thin-film coatings may suffer from adhesion problems and show a limited wavelength or angle dependency. Additionally for some applications (e.g. in the deep-UV), the available material selection for thin-film is also limited. An alternative which allows to over-come the mentioned disadvantages are sub-wavelength structured AR-surfaces. These structures are found in nature on the corneal surfaces of night active insects and which therefore are also called “moth-eye structures”. Here we report on different fabrication technologies which enables the creation such sub-wavelength periodic structures and which are acting optically as an effective material with gradual change of the refractive index. A very flexible and beneficial manufacturing process of these sub-wavelength structures relies on a combination of block copolymer micelle nanolithography (BCML) followed by a reactive-ion-etching (RIE) process [1, 2]. The application area of these result-ing structures can even be extended by improving the regular patterning of quasi-hexagonal micellar nano-structures using ultrasonication [3]. Additionally we discuss the influence of in-homogeneities to the optical properties of the AR-surfaces and the application of the artificial moth-eye structures to refractive lenses, microstructured elements and flexible lenses made of soft optical materials.

[1] T. Lohmüller, M. Helgert, M. Sundermann, R. Brunner, and J. P. Spatz, "Biomimetic Interfaces for High-Performance Optics in the Deep-UV Light Range," Nano Letters 8, 1429-1433 (2008).

[2] Ch. Morhard, C. Pacholski, D. Lehr, R. Brunner, M. Helgert, M. Sundermann, and J. P. Spatz, “Tailored antireflective biomimetic nanostructures for UV applications,” Nanotechnology 21, 425301 (6pp), (2010)

[3] Ch. Williges, W. Chen, Ch. Morhard, J. P. Spatz, and R. Brunner; “Increasing the Order Parameter of Quasi Hexagonal Micellar Nanostructures by Ultrasound Annealing”; Langmuir, 29 (4), pp 989–993, (2013)

1 µm

Artificial moth-eye structure (right) and natural model (left). The sub-wavelength periodic structure acts as an effective medium and offers anti-reflective properties.

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MUELLER MATRIC SPECTROSCOPIC ELLIPSOMETRY FOR PHOTOMASK EVALUATION Anett Heinrich1, I. Dirnstorfer1, J. Bischoff2, K. Meiner3, U. Richter3, T. Mikolajick1, 4

1 NaMLab GmbH, 01187 Dresden, Germany 2 Osires, 98693 Ilmenau, Germany 3 SENTECH Instruments GmbH, 12489 Berlin, Germany 4 Institute of Semiconductor and Microsystems, TU Dresden, 01187 Dresden, Germany

Anett.Heinrich@namlab.com Spectroscopic ellipsometry is a well studied and commonly used technique in a wide field of applications, especially in the semiconductor and thin film research field. However, standard spectroscopic ellipsometry is not valid for anisotropic samples. To evaluate anisotropic samples and determine the complete information about the polarization of light, Mueller matrix spectroscopic ellipsometry (MMSE) has to be applied. It is a powerful technique for the study and accurate determination of the dielectric function, optical properties and geometric characteristics of anisotropic materials and complex systems [1]. In this work, we apply MMSE to examine undesired asymmetries in line-space structures on photomasks, i.e. line edge roughness (LER). LER is a critical structural parameter on photomasks since it has a significant impact on the performance of the final chip. The standard method to determine LER is scanning electron microscopy (SEM). Unfortunately, this is an expensive and time consuming technique with measurement inaccuracies due to interactions between the electrons and the photomask especially on glass blanks. Alternatively, MMSE is a powerful, highly accurate technique to determine LER on photomasks [2]. The Mueller matrix (MM) elements are measured within the complete azimuth angle range (0 – 360°) and a wavelength range from 300 nm to 980 nm as shown in the figure. The results are presented in polar coordinates of the azimuth angle and wavelength. It is found that LER significantly impacts the MM elements, which is interpreted by the increase of the isotropic character of the array. Furthermore, it is shown that different types of LER features (single sided, anti- and fully correlated LER) can be distinguished by their selective impact on the MM. The experimental data are confirmed by rigorous coupled wave analysis (RCWA) simulations.

[1] Laskarakis, A. et al., Thin Solid Films, 455-456 (2013). [2] Heinrich, A. et al., Proc. of SPIE Vol. 8886 (2013).

s

The MM element m22 is shown in polar coordinates of the wavelength and azimuth angle for 3 different amplitudes of fully correlated LER.

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INVESTIGATION OF THE FIRST STEP NUCLEATION OF TWO DIMENSIONAL GOLD NANOISLAND ANISOTROPIC FILMS BY SPECTROSCOPIC ELLIPSOMETRY Yann Battie1, A. En Naciri1, W. Chamorro2, 3, D. Horwat2, 3

1 Université de Lorraine, Institut Jean Barriol, LCP-A2MC, 1 Bd Arago, 57070 Metz, France 2 Université de Lorraine, Institut Jean Lamour, UMR7198, Nancy, F-54011, France 3 CNRS, Institut Jean Lamour, UMR7198, Nancy, F-54011, France

yann.battie@univ-lorraine.fr Supported metallic nanoislands exhibit strong optical absorption due to the surface plasmon resonance induced by the collective oscillation of their conduction electrons. The characteristics of the plasmon resonance depend on the refractive index of the surrounding medium as well as the nanoparticle size, shape and organisation. Despite their used as building blocks of photonic devices, the theoretical description of the optical properties of these complex films remains a great challenge. In this work, an alternative effective medium theory is introduced to describe the optical properties of a two dimensional array of metallic nanoislands. This two dimensional effective medium theory (2DEMT), which is based on a mean field approach [1], takes into account both, the optical anisotropy induced by the nanoisland orientation and their shape distribution [2]. 2DEMT is successfully used to interpret ellipsometric measurements performed on gold nanoislands sputtered on a silicon substrate. This model gives a better description of the optical properties of the nanoisland film than conventional effective medium theories By coupling ellipsometric to AFM measurements, we show that the first step of nanoislands nucleation involves a Volmer-Weber growth mechanism. The optical anisotropy of uniaxial nanoisland films was correlated to the in plane preferential self-orientation of gold nanoislands. Indeed, we unambiguously demonstrate that the optical birefringence and dichroïsm (see figure) are due to the splitting of the plasmon resonance into two modes: the transversal and the longitudinal modes of gold nanoislands distributed in shape.

[1] Choy, T. C. Effective medium theory: principles and applications; Oxford University Press, 1999

[2] Goncharenko, A. V.; Lozovski, V. Z.; Venger, E. F. Effective dielectric response of a shape-distributed particle system. J. Phys.: Condens. Matter 2001, 13, 8217–8234.

(a, b, c, d) Evolution of the nanoislands morphology measured by AFM for different sputtering time. (e) Birefringence and (f) dichroïsm of nanoisland films for different sputtering times.

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COMBINATORIAL QCM-D/GE-STUDY OF SWELLING AND PROTEIN ADSORPTION OF POLYMER BRUSHES GRAFTED ONTO NANOSTRUCTURED SURFACES Meike Koenig1, 2, Tadas Kasputis3, Daniel Schmidt3, Keith Brian Rodenhausen3, Klaus-Jochen Eichhorn1, Angela K. Pannier3, Mathias Schubert3, Manfred Stamm1, 2, Petra Uhlmann1

1 Leibniz-Institut für Polymerforschung Dresden, 01069 Dresden, Germany. 2 Technische Universität Dresden, 01062 Dresden, Germany. 3 University of Nebraska-Lincoln, Lincoln, NE 68588, USA.

uhlmannp@ipfdd.de Exhibiting a reversible swelling-deswelling behavior upon external stimuli, polymer brushes offer a route to create stimuli-responsive coatings and have therefore been the subject of intense research [1]. An interesting new class of functional hybrid materials is created by combination of these systems with 3D-nanostructures possessing tunable intricate features such as porosity, surface roughness, and surface chemistry [2], which can be tailored to the specific needs of the applications. We grafted pH-responsive poly (acrylic acid) (PAA) guiselin brushes or temperature-responsive poly (N-isopropylacryl amide) (PNIPAAm) onto silicon sculptured thin films (STF) fabricated by glancing angle deposition (GLAD) [3]. Generalized ellipsometry (GE) was employed to characterize the fabrication of the STF as well as the grafting of polymer brushes to the nanostructures. A modified anisotropic Bruggemann - EMA was used to model GE measurements, providing access to the structural parameters and the volume fractions of the constituents. For in situ-studies of swelling characteristics and protein adsorption, combinatorial GE and quartz crystal microbalance with dissipation mode (QCM-D) measurements were conducted. The changes in birefringence upon swelling of the polymer and adsorption of a model protein (Bovine Serum Albumin, BSA) could be fitted by changes in two model parameters, the fraction of organic material f(organic) and the thickness of a top-layer above the nanocolumns d(Top). Because of its sensitivity and non-destructive aspect, GE was found to be a most suitable characterization tool for these novel functional coatings. We acknowledge funding of this work by DFG and NFS within the “Materials World Network” and the EPSCoR project.

[1] O. Azzaroni, J. Polym. Sci. A1, 50, 3225 (2012). [2] Schmidt, D. et al., Appl.Phys.Lett. 94, 011914 (2009). [3] Kasputis, T., Koenig, M. et al., Journal of Physical Chemistry C, 117, 13971 (2013).

Scheme of polymer brush swelling on STF.

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INVESTIGATION OF ELECTROMAGNETIC MODES IN MULTIFERROIC OXIDES BY FAR INFRARED MUELLER-MATRIX ELLIPSOMETRY Andrei Sirenko Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102, United States sirenko@njit.edu Measurements of the complex functions of electrical permittivity ( )ε ω and magnetic permeability ( )µ ω using a combination of ellipsometry and transmittance can reveal details of the coupling between magnetic and electric excitations in magnetoelectric materials. Recently we developed a full-Mueller matrix far-IR spectroscopic ellipsometry at the U4IR beamline of the National Synchrotron Light Source (NSLS) in Brookhaven National Laboratory (BNL). The main application of this ellipsometer is for antiferromagnetic, multiferroic, and magnetoelectric materials with ( ) 1µ ω ≠ and for materials with non-zero components of the magnetoelectric tensor ( ) 0α ω ≠ . An exceptional brightness of synchrotron radiation allows for measurements in a broad spectral range between about 10 and 4,000 cm-1. For the quantitative analysis of the optical spectra for materials with ( ) 1µ ω ≠ and ( ) 0α ω ≠ we developed an advanced modelling approach, which is based on the Berreman’s 4 4× matrix formalism. Our approach allows to model experimental optical spectra, including spectra of electromagnons in anisotropic magnetic materials, and to separate ( ), ( )ε ω µ ω and ( )α ω tensor components of the complex dielectric response. Experimental data for a number of multiferroic and magneto-electric crystals, such as RMnO3, RMn5O5, and R3Fe5O12 garnets (R=rare earth) will be presented. In addition to purely dielectric (phonons) and magnetic modes (magnons), we observed several hybrid modes with a mixed magnetic and electric dipole activity. The hybrid modes originate from the crystal field transitions in the f-shell of the R3+ ions modified by exchange interaction with magnetic ions (Fe, Mn).

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SPIN-DENSITY-WAVE-INDUCED ANOMALIES IN THE OPTICAL CONDUCTIVITY OF AFe2As2, (A = Ca, Sr, Ba) SINGLE-CRYSTALLINE IRON PNICTIDES Aliaksei Charnukha1, 2, D. Proepper1, T. I. Larkin1, D. L. Sun1, Z. W. Li1, C. T. Lin1, T. Wolf3, B. Keimer1, A. V. Boris1

1 Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany

2 Leibniz Institute for Solid State and Materials Research, IFW, D-01069 Dresden, Germany 3 Karlsruhe Institute of Technology, Institut für Festkörperphysik, D-76021 Karlsruhe, Germany

a.charnukha@ifw-dresden.de We report the complex dielectric function of high-quality AFe2As2 (A = Ca, Sr, Ba) single crystals with TN = 150 K, 200 K, and 138 K, respectively, determined by broadband spectroscopic ellipsometry at temperatures from 10 K to 300 K and wavenumbers from 100 cm-1 to 52000 cm-1. In CaFe2As2 we identify the optical spin-density--wave gap 2ΔSDW = 1250 cm-1. The 2ΔSDW/(kBTN) ratio, characterizing the strength of the electron-electron coupling in the spin-density--wave state, amounts to about 12 in CaFe2As2, significantly larger than the corresponding values for the SrFe2As2 and BaFe2As2 compounds: 8.7 and 5.3, respectively. We further show that, similarly to the Ba-based compound, two characteristic SDW energy gaps can be identified in the infrared-conductivity spectra of both SrFe2As2 and CaFe2As2 and investigate their detailed temperature dependence in all three materials. This analysis reveals the existence of an anomaly in CaFe2As2 at a temperature T* = 80 K, well below the Neel temperature of this compound, which implies weak coupling between the two SDW subsystems. The coupling between the two subsystems evolves to intermediate in the Sr-based and strong in the Ba-based material. The temperature dependence of the infrared phonons reveals clear anomalies at the corresponding Neel temperatures of the investigated compounds. In CaFe2As2, the phonons exhibit signatures of SDW fluctuations above TN and some evidence for anomalies at T*. Investigation of all three materials in the visible spectral range reveals a SDW--induced suppression of two absorption bands systematically enhanced with decreasing atomic number of the intercalant. A dispersion analysis of the data in the entire spectral range clearly shows that CaFe2As2 is significantly more metallic than the other two compounds. Our results single out CaFe2As2 in the class of ThCr2Si2-type iron-based materials by demonstrating the existence of two weakly coupled and extremely metallic electronic subsystems.

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OPTICAL RESPONSE OF THE TOPOLOGICAL INSULATOR Bi2(TexSe1-x)3 THIN FILMS GROWN EPITAXIALLY ON BaF2 SUBSTRATES Adam Dubroka1, M. Hronček1, O. Caha1, P. Friš1, V. Holý2, H. Steiner3, M. Ul-Hassan3, G. Bauer3, G. Springholz3, J. Sanchez-Barriga4, O. Rader4, T. N. Stanislavchuk5, A. A. Sirenko5, J. Humlíček1

1 Masaryk University, Department of Condensed Matter Physics and CEITEC - Central European Institute of Technology, Kotlářská 2, 61137 Brno, Czech Republic

2 Charles University, Department of Electronic Structures, Praha, Czech Republic 3 Johannes Kepler University of Linz, Institut für Halbleiter- und Festkörperphysik,

Altenbergerstrasse 69, 4040 Linz, Austria 4 Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II,

Albert-Einstein-Straße 15, 12489 Berlin, Germany 5 New Jersey Institute of Technology, Department of Physics, Newark, New Jersey 07102,

United States dubroka@physics.muni.cz We have studied a series of thin films of topological insulators Bi2Te3, Bi2Se3 and their alloys Bi2(TexSe1-x)3 grown on BaF2 substrates. We have used spectroscopic ellipsometry and reflectivity measurements in order to probe the optical response of the films between 40 cm-1 and 6.5 eV. The spectra were analyzed using the Drude-Lorentz model in the infrared range. The infrared response is dominated by bulk charge carriers. The broadening of the Drude component, γD, is essentially independent of the charge carrier concentration. Its dependence on the tellurium content x in the alloy seems to be mainly determined by alloy scattering. In addition, the correlation of the trend in γD(x) with the magnitude of the fundamental band gap suggests that the scattering rate is influenced by the band structure. The real part of the pseudo-dielectric function measured by ellipsometry measured at the angles of incidence between 50-80° on a 533 nm thick Bi2(TexSe1-x)3 layer with x = 74%, grown on BaF2 substrate (solid lines) and the fit with the Drude-Lorentz model (broken lines). The dependence of the retrieved Drude broadening γD on the tellurium content x is shown in the inset.

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OBLIQUE INCIDENCE REFLECTANCE DIFFERENCE SPECTROSCOPY (OIRD) FOR REAL-TIME OPTICAL OBSERVATION OF THE FORMATION OF THE CONDUCTING INTERFACE BETWEEN LaAIO3 AND SrTiO3 Chencheng Xu2, X. D. Zhu1, Sebastian Wicklein2, Felix Gunkel2, Rui Xiao1, Regina Dittmann2

1. University of California, Department of Physics, Davis, California 95616, U.S.A. 2. Peter Grünberg Institute (PGI), Research Centre Jülich, D-52425 Jülich, Germany

c.xu@fz-juelich.de Oblique incidence reflectance difference spectroscopy (OIRD) [1] is a method based on the modulation of the polarization of the incident light, which allows for the real-time observation of the reflectance change for p and s polarized light on surfaces with high time resolution. We adapted this system to our pulsed laser deposition chamber, which enables us to monitor changes in the dielectric properties of oxide thin films during growth or post-annealing treatments. We carried out OIRD measurement during the growth of LaAlO3 on SrTiO3. We observed a change in the slope of the reflectance difference signal between 3 and 4 unit cells which might be related to the fact that 4 unit cells is the critical thickness for the generation of the conductive interface between LaAlO3 and SrTiO3 [2]. Furthermore, in some cases we observe a step-like change of the OIRD signal in the same thickness range. We will discuss the interrelation between the optical signal and the electronic reconstruction at the LaAlO3/SrTiO3 interface. One possible scenario for the observed change of the slope is that residual fields present in the heterostructures causes a difference in the dielectric constant of the first 3 LaAlO3 layers by the electro optical Kerr effect [3]. The observed step-like change of the reflectance difference signal might be explained by the change in reflectivity of the interface which is induced by the interface electronic reconstruction.

[1] X. D. Zhu, Y. Y. Fei, X. Wang, H. B. Lu, G. Z. Yang, Physical Review B 75, 245434 (2007) [2] C. W. Bark, et al., Proceedings of the National Academy of Sciences 108, 4720 (2011) [3] Zhu et al., submitted

Upper panel: RHEED intensity of specular spot. Middle panel: first harmonics of OIRD. Lower panel: first harmonics of OIRD without linear part.

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OPTICAL CHARACTERIZATION AND MODELING OF NANOSTRUCTURES FOR PHOTOVOLTAIC APPLICATIONS Martin Foldyna CNRS, Ecole Polytechnique, Laboratory of Physics of Interfaces and Thin Films, 91128 Palaiseau, France martin.foldyna@polytechnique.edu The recent focus of many countries in the world on the expansion of their renewable energy portfolio has led to a significant boost of the photovoltaic industry. Indeed, the solar energy represents a very promising renewable energy source for the future with its virtually infinite delivery of the energy exceeding today’s world energy consumption by orders of magnitude. Recent progress in the photovoltaic industry has led to 50% reduction of the cost of silicon solar panels between years 2006 and 2011 [1, 2]. Nevertheless, a further reduction of the cost per watt requires not only a decreasing module fabrication cost, but also new and innovative concepts increasing the energy conversion efficiency of solar cells. A new concept of radically different device architecture has been introduced with radial junction solar cells based on nanowires. The carrier collection in the radial direction enhanced by a stronger built-in field, together with an efficient light trapping inside nanowire arrays, demonstrates the innovative approach to low-cost high-efficiency solar cells [3]. Nevertheless, the increase of the performance of silicon nanowire solar cells requires optimization of the light trapping inside nanowires. The optimization of the critical dimensions of silicon nanowires as well as the demonstration of the impact of the nanowire disorder will be presented. Results include a comparison with experimental data obtained on nanowire structures fabricated using a vapor-liquid-solid approach as well as the demonstration of a new concept based on the presented ideas.

[1] McCrone, “Solar surge drives record clean energy investment in 2011,” Bloomberg New Energy Finance, 2012. https://www.bnef.com/PressReleases/view/180.

[2] M. Hanis, J. Blanton, N. Rinaldi, T. Kimbi, S. Fenn, J. Baca, W. Lent, “Solar energy facts: year in review 2011,” Solar Energy Industry Assoc., 2012.

[3] S. Misra, L. Yu, M. Foldyna, P. Roca i Cabarrocas, Sol. En. Mat. & Sol. Cells 118, 90 (2013).

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PROGRESS IN SPECTROSCOPIC ELLIPSOMETRY FOR THE IN-SITU REAL-TIME INVESTIGATION OF ATOMIC LAYER DEPOSITIONS Marcel Junige1, Varun Sharma1, Daniel Schmidt2, Matthias Albert1, Mathias Schubert2, Johann W. Bartha1

1 Technische Universität Dresden, Institute of Semiconductors and Microsystems (IHM), 01062 Dresden, Germany

2 University of Nebraska-Lincoln, Department of Electrical Engineering, Lincoln, Nebraska 68588-0511, USA

marcel@junige.de In Atomic Layer Deposition (ALD) the educts of an overall film-producing reaction are fed into a reactor individually separated and alternately one after the other. The thus isolated and ideally self-limiting partial reactions at the gas-solid surface provide unique capabilities for ultra-thin functional coatings in nanotechnology. The most prominent benefits are a high uniformity (i.e. conformity even on sophisticated 3D structures of smallest dimension, complex shape or high aspect ratio; and homogeneity on large-sized substrates) as well as an extraordinary film thickness control in the sub-nanometer range. Spectroscopic Ellipsometry (SE) is a non-destructive, non-invasive as well as contactless measurement technique, which is fast, accurate, precise, and highly sensitive even to the smallest change on a solid-state surface. Consequently, SE is ideally suited for the characterization of a material deposition, modifying an initially pristine surface towards the film-covered final state at exactly the place (in situ) and the time where the respective reactions occur. In this study, we present an algorithm for the in-situ real-time SE, which includes the calibration of all ex-situ and additional in-situ (e.g. window) elements in the rotating compensator ellipsometer’s light path; the fine correction of experiment specific deviations (like alignment or temperature effects); the correction of inaccuracies due to the use of one fixed polarizer position; the acquisition of ellipsometric spectra with the fastest possible sampling rate; the evaluation of the experimental dynamic data time slice by time slice; and, finally, the post-processing of a desired model parameter’s time-resolved results. In conclusion, we revealed the optical layer thickness of Al2O3, TaN and Ru, respectively, in the course of one ALD cycle. This enabled the investigation of surface actions during the precursor adsorption, ligand removal, and purging periods with a desired high time resolution.

Optical layer thickness in the course of one tantalum nitride ALD cycle as revealed from in-situ real-time SE. The precursor and co-reactant exposure are indicated by the red and green bar, respectively.

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BiFeO3-COATED PHOTOCAPACITIVE MIS DIODES WITH ADDED NONVOLATILE FUNCTIONALITY Laveen Prabhu Selvaraj1, T. You1, V. John1, H. Zeng2, D. Bürger1, I. Skorupa1, A. Lawerenz3, K. Ettrich3, O. G. Schmidt1 ,4, H. Schmidt1

1 Chemnitz University of Technology, Faculty of Electrical Engineering and Information Technology, 09107 Chemnitz, Germany

2 University of Electronic Science and Technology of China, State Key Laboratory of Electronic Thin Films and Integrated Devices, 610054 Chengdu, China

3 CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, 99099 Erfurt, Germany 4 Institute for Integrative Nanosciences, IFW Dresden, 01069 Dresden, Germany

laveen-prabhu.selvaraj@s2011.tu-chemnitz.de BiFeO3 is one of the few materials that exhibit ferroelectricity and antiferromagnetism at room temperature. The remanent polarization of BiFeO3 amounts to 50 µC/cm2 [1]. Metal-BiFeO3-metal thin film structures can be switched between a high resistance state (HRS) and a low resistance state (LRS), when a positive and negative writing bias is applied, respectively. This bipolar resistive switching is nonvolatile and has attracted increasing attention [2]. The current investigation deals with the effect of light-irradiation on the capacitance of BiFeO3-coated metal-insulator-semiconductor (MIS) diodes (inset 2 in figure). N-type conducting BiFeO3 thin films of nominal thickness 70, 140, 210, 280, 350 and 490 nm have been grown by pulsed laser deposition at a substrate temperature of 650° C and under oxygen partial pressures of 0.013 mbar on p-type conducting float-zone, 100 silicon wafers substrates (3-6 Ω cm) having an 163 nm thick SiN layer with an index of refraction of 1.95 [3]. The thickness and optical constants of all layers of the MIS diodes have been investigated using spectral ellipsometry measurements with a VASE ellipsometer. Circular Au contacts were deposited by magnetron sputtering. The DC bias for the capacitance measurements was swept from +10 V to -15 V and back under different light-irradiation at a sweep rate of ca. 59 mV/s. It has been found that under dark conditions two nonvolatile capacitance minima can be found at -3.8 V and at -6.8 V possibly when the BiFeO3 is in the HRS and LRS state, respectively (see figure). Under illumination the capacitance at the two minima increases in the visible spectral range in dependence on the wavelength, illumination intensity, BiFeO3 thickness and BiFeO3 resistance state. The retention measurement result (inset 2) shows non-volatile memory in capacitance which can be used for photocapacitive detectors.

Experimental capacitance vs voltage data of n-BiFeO3/SiN1/p-Si/Au diodes for a test frequency of 10 kHz. In the sweep range from 10 to -15 V (branch 1) and from 10 to -15 V (branch 2) under light-irradiation. Inset 1: Schematic diode structure. Inset 2: Retention measurement of the capacitance in branch 1 and branch 2 at the two capacitance minima -3.8 V and -6.8 V under dark conditions.

29

CHARACTERIZATION OF MULTI-LAYER ILD STACK BY SPECTROSCOPIC ELLIPSOMETRY IN NANOELECTRONIC MANUFACTURING Dmitriy V. Likhachev GLOBALFOUNDRIES Dresden Module One LLC & Co. KG, Wilschdorfer Landstr. 101, D-01109 Dresden, Germany dmitriy.likhachev@globalfoundries.com The accurate and stable measurements of inter-layer dielectric (ILD) films thicknesses and optical properties in a multi-layer stack have been always a key factor in semiconductor development and manufacturing. Spectroscopic ellipsometry is one of the most adapted optical metrology techniques to perform such measurements but it requires use of one of the multi-parameter non-linear optimization methods due to its indirect nature. It creates a big challenge for analysis of multi-layer structures since the number of simultaneously determined model parameters is restricted due to parameter cross-correlations. In this work a simple way to reduce thicknesses correlations between the dielectric films in the multi-layer ILD film stack during the ellipsometric analysis has been presented. The method is based on inclusion of additional thin absorbing metal layer into the multi-layer structure in order to suppress the inter-layer correlations, thereby allowing an accurate determination of the thicknesses of individual films in the thin-film stack. We reported the successful characterization of the film stack with up to five-layer film structure in which four of the films are dielectric by ex situ single-angle spectroscopic ellipsometer. The optical characterization of all layers in the spectral range of 200–800 nm (6.20–1.55 eV) has been performed using an “additive” thin-film stack approach which takes into consideration possible differences in films optical properties compared to ones extracted by using conventional single-layer characterization method. The consistency of characterization results for all films has been demonstrated. The uniqueness of obtained ellipsometric solutions and accuracy of established optical models for the multi-layer thin-film stack have been also investigated. The reduction in uncertainties for all dielectric films clearly indicates a decrease in cross-correlations of the model parameters.

30

OPTICAL TRANSITIONS OF π-CONJUGATED ORGANIC MATERIALS FOR SOLAR CELLS DETERMINED BY SPECTROSCOPIC ELLIPSOMETRY Fatima Bencheikh-Aboura, D. Duché, J. J. Simon, L. Escoubas Université Aix-Marseille, IM2NP, CNRS-UMR 7334, Marseille, France fatima.bencheikh-aboura@im2np.fr Solar cells based on interpenetrating blend of polymer and soluble fullerene derivative have recently attracted much attention. This is due to their low cost, their light weight and their easy solution phase processability. In this work, we study the optical properties of fullerene derivatives PC60BM ([6,6]-phenyl-C61-butyric acid methyl ester) and the PC70BM ([6,6]-Phenyl-C71-butyric acid methyl ester) and polymers P3HT (poly(3-hexylthiophène)) and PTB7 (polymer thieno[3,4-b]thiophene/benzodithiophene) that are the electron acceptors and donnors respectively. These organic materials are π-conjugated semiconductors. The broad use of these materials needs quantitative understanding of their optical and electronic properties. We choose the P3HT and the PTB7 as polymers because the first is the most studied polymer [1] and the second is the polymer which gives of the highest reported efficiency for polymer:fullerene solar cells[2]. In this study, we show that it is possible to determine optical transitions by spectroscopic ellipsometry measurement and modeling. Thus, we could identify intermolecular and intramolecular transitions occuring during the process of light absorption by the fullerene derivatives and the polymers. Variable angles spectroscopic ellipsometry measurements (from 300 nm to 900 nm) were perfomed using a SOPRA GES5 5, rotating polarizer ellipsometer (RPE). The films were prepared by spin coating on glass substrates. Understanding the optical properties of the polymers and the fullerene derivatives and following the evolution of the optical transitions enable us to understand the change in the optical properties of organic donor semiconductors and their blends with different acceptors. Therefore we can access to information about the crystallization and the nano-morphology of the resulting films.

[1] M. T Dan, et al.; J. D. Chem. Rev., 113, 3734 [2] Z. He et al.; Nat. Photo., 6, 591, 2012.

Chemical structure of electron donor (a) P3HT, (b) PTB7 and electron acceptor (c) PC60BM, (d) PC70BM

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LOW-ENERGY INTERBAND TRANSITIONS IN THE INFRARED RESPONSE OF PNICTIDE SUPERCONDUCTORS Premysl Marsik1, C. N. Wang1, M. Roessle1, M. Yazdi-Rizi1, R. Schuster1, K. W. Kim2, A. Dubroka3, D. Munzar3, T. Wolf4, X. H. Chen5, C. Bernhard1

1 University of Fribourg, Fribourg, Switzerland 2 Chungbuk National University, Cheongju, Korea 3 Masaryk University, CEITEC - Central European Institute of Technology, Brno, Czech

Republic 4 KIT, Karlsruhe, Germany 5 University of Science and Technology, Hefei, China

premysl.marsik@unifr.ch We studied the doping and temperature (T) dependence of the infrared (IR) response of Ba(Fe1-xCox)2As2 single crystals, using mid- and far- infrared ellipsometry. We show that a weak band around 1000 cm-1 that was previously interpreted in terms of interaction of the charge carriers with magnetic excitations or of a pseudogap, is rather related to low-energy interband transitions. Detailed study of the behavior of the relatively weak feature was enabled by using high precision differential ellipsometric measurements and modeling. Specifically, we show that this band exhibits a similar doping and T-dependence as the hole pockets seen by angle resolved photoemission spectroscopy (ARPES). Notably, we find that it vanishes as a function of doping near the critical point where superconductivity is suppressed in the overdoped regime. Our IR data thus provide bulk specific information (complementary to the surface sensitive ARPES) for a Lifshitz transition.

32

FANO RESONANCES IN THE INFRARED SPECTRA OF PHONONS IN HYPER-KAGOME NA3Ir3O8 Daniel Pröpper1, A. N. Yaresko1, T. I. Larkin1, T. N. Stanislavchuk2, A. A. Sirenko2, T. Takayama1, 3, A. Matsumoto1, 3, H. Takagi1, 3, B. Keimer1, A. V. Boris1

1 Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany 2 New Jersey Institute of Technology, Newark, USA 3 University of Tokyo, Japan

d.proepper@fkf.mpg.de We report the complex dielectric function of high-quality Na3Ir3O8 single crystals determined by spectroscopic ellipsometry in the spectral range from 15 meV to 2 eV. The far-infrared phonon spectra exhibit highly asymmetric line shapes characteristic of Fano resonances. With decreasing temperature, we observe a sharp increase of the infrared intensity of the Fano-shaped phonon modes accompanied by concomitant changes in the low energy electronic background, formed by electronic transitions between Ir 5d t2g bands of a mostly Jeff = 1/2 character. The role of the complex Hyper-Kagome lattice structure and strong spin-orbit coupling is considered.

33

PROBING INTERFACIAL PROPERTIES AT METAL/ELECTROLYTE INTERFACES OF REACTIVE MATERIALS: EXAMPLES FROM ZINC AND COPPER Ying Chen, Cigdem Toparli, Andreas Erbe Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf a.erbe@mpie.de One of the challenges preventing an atomistic understanding of electrochemical interfaces is the limited amount of suitable characterisation techniques which are sensitive, fast, and yield details about interfacial structures and processes. This work presents experimental results, mainly derived from the coupling of electrochemical experiments and spectroscopic ellipsometry, on the oxide growth on zinc, and the accompanying evolution of oxide electronic structure, comparing different atmospheres and aqueous carbonate electrolyte [1, 2, 3]. An analysis scheme is introduced which enables the determination of a layer thickness without optical model for non-absorbing layers on a metallic substrate. This scheme is applied (a) under potentiodynamic polarisation of the oxide-covered surface, to show a linearly with electrode potential of the layer thickness and (b) in potential jump experiments, where the layer thickness reaches its almost final value within seconds after the potential jump [1]. In addition to the layer thickness, the absorption spectra show a slow (~30 min) development of the main electronic absorption of ZnO. The kinetics is independent of the potential difference applied in the jump experiments. Further, a very similar kinetics of the development of the absorption spectrum is found during atmospheric oxidation of Zn [2]. In conclusion, structural evolution of the oxide layer is independent of the thickness increase of the layer: there are always at least two different time scales for the two processes. Whether this feature is special to Zn or more universal needs to be evaluated on other materials. Cu is an interesting candidate in that respect, as it possesses two different oxides.

[1] Y. Chen, A. Erbe, Surf. Sci. 607 (2013), 39-46 [2] Y. Chen, P. Schneider, A. Erbe, Phys. Status Solidi A 209 (2012), 846-853 [3] Y. Chen, P. Schneider, B.-J. Liu, S. Borodin, B. Ren, A. Erbe: Phys. Chem. Chem. Phys. 15,

(2013) 9812-9822

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GENERALIZED ELLIPSOMETRY OF SEMIPOLAR AlGaN Juliane Klamser1, M. Feneberg1, R. Goldhahn1, J. Stellmach2, M. Frentrup2, S. Ploch2, F. Mehnke2, T. Wernicke2, M. Kneissl2

1 Otto-von-Guericke-Universität Magdeburg, Institut für Experimentelle Physik 2 Technische Universität Berlin, Institut für Festkörperphysik

juliane.klamser@st.ovgu.de We present generalized spectroscopic ellipsometry data obtained from the anisotropic semiconductor material system aluminium gallium nitride (AlGaN) where the optical axis is tilted in respect to the sample surface. These samples are available as thin epitaxial films with thickness of few micrometers on the foreign substrate sapphire. Several samples spanning the whole composition range between GaN and AlN are investigated. While the (11-22) orientation of the AlGaN surface allows for alignment of the optical axis parallel to the plane of incidence, no perpendicular alignment is possible. At the same time, the optical axis of the as well anisotropic sapphire substrate, is pointing in a different direction. This challenging sample geometry requires careful measurement of the main and the secondary elements of the Jones matrix and in turn influences strongly data analysis and modelling of the dielectric function. As result of the evaluation of the measurements we present the successfully separated ordinary and the extraordinary tensor components of the dielectric function. We not only succeeded in fitting model dielectric functions to experimental data but also present point-by-point fitted dielectric functions of several AlGaN samples. The valence band structure of AlGaN governing optical selection rules and thus the dielectric function is expected to show a crossing at certain but unknown aluminium concentration. Our study experimentally narrows the possible band crossing range in AlGaN.

Shown are experimental data (red) and corresponding point-by-point-fits (black) of the pseudo real (a and b) and imaginary (c and d) parts of the complex dielectric function for Al0.63Ga0.37N. The sample orientation in the left column (a and c) is the optical axis parallel to the plane of incidence, in b and d the projection of the optical axis is perpendicular to the plane of incidence.

35

MUELLER MATRIX ELLIPSOMETRY OF MONOCLINIC Cu(H2O)2(C2H8N2)SO4 CRYSTAL Kamil Postava1, R. Sykora1, D. Legut1, A. Orendacova2, R. Tarasenko2, J. Pistora1

1. Technical University of Ostrava, Department of Physics and Nanotechnology Centre, 2. 17. listopadu 15, 708 33 Ostrava - Poruba, Czech Republic 3. P. J. Šafárik University, Faculty of Science, Center of Low Temperature Physics, Park

Angelinum 9, 041 54 Košice, Slovakia kamil.postava@vsb.cz Cu(H2O)2(C2H8N2)SO4 attracts strong interest due to its low-dimensional magnetic properties. Recently [1, 2], the system was identified as a quasi-one-dimensional S = 1/2 Heisenberg antiferromagnetic insulator. The structure possesses a monoclinic symmetry with the axis inclination (angle beta) of 105.5° [3]. Precise knowledge of the material optical functions is important for confirmation and improvement of ab-initio models of electronic states, e.g. with respect to the width of the band gap. Mueller matrix spectra in the range from 193 to 1700 nm was obtained using RC2 spectroscopic ellipsometer Woollam for different angles of incidence and azimuthal angles during 360° rotation of the sample. We have extracted the optical spectra of the permittivity tensor components from row Mueller matrix data. Obtained spectra are compared with the ab-initio calculations based on the density function theory [4].

[1] R. Sykora, D. Legut, U. D. Wdowik, Exchange Interactions in a Low-Dimensional Magnetic System Cu(H2O)2(en)SO4 (accepted in Acta PhysicaPolonica)

[2] R. Sykora and D. Legut, Magnetic Interactions in a Quasi-One-DimensionaAntiferromagnet Cu(H2O)2(en)SO4 (accepted in J. Appl. Phys.).

[3] V. Manriquez et al. J. Chem. Cryst. 26, 15 (1996). [4] P. Hohenberg and W. Kohn, Phys. Rev. 136, B864 (1964).

36

WAS THE SKY ALWAYS BLUE? THE ROLE OF CIRCULAR POLARIZED LIGHT IN THE EVOLUTION OF LIFE Bruno Gompf Universität Stuttgart, Physikalisches Institut, Stuttgart, Germany b.gompf@physik.uni-stuttgart.de The question “How life originates on earth” is strongly related to the question “Why were left handed molecules selected for its architecture”. In the absence of some type of directing template known chemistry always yields equal amounts of left- and right handed molecules (racemic mixture), but life’s proteins today exclusively implement left-handed amino acids. Why left? Since the famous statement of Louis Pasteur: “Optical activity is a signature of life” there exist a large number of speculations what physical mechanism tips the balance during the evolution of life inevitable to the left. It is now commonly accepted that without preexisting chiral purity, self-replication characteristic for living matter could not occur. But what breaks the symmetry during the evolution of life on the early earth? In the talk I will describe why circular polarized (cp) light is one of the most promising candidates to answer this question. Whereas Rayleigh-scattering on air-molecules leads to linear polarization (blue sky), Mie-scattering can be a natural source of cp. For example, in astronomy, high degrees of cp in the near infrared were observed in dust clouds in star forming regions, and irradiation of chiral amino acids with cp UV-light leads to an excess of one handedness. Up to now, there is no systematic research on natural sources of cp-light and even the title question is unanswered: Was the sky always blue (linear polarized), or did large dust clouds lead to a much higher degree of circular polarization on the early earth.

37

ELLIPSOMETRY-SCATTEROMETRY THEORY: RCWA, C-METHOD AND THE GRATING SOLVER UNIGIT Joerg Bischoff MPI für Sonnensystemforschung Göttingen und Osires Ilmenau Rigorous modeling methods attain more and more importance in scatterometry and ellipsometry. Out of many methods, the Rigorous Coupled Wave Method (RCWA) is widely used preferably in semiconductor metrology. It is very universal, mature and robust. One of its specific features is the discretization of a grating in vertical direction also known as slicing. On the one hand, the slicing enables to access almost all kind of patterned multilayer stacks including overhanging profiles and multilayer coatings. On the other hand, it may slow done the computation considerably because each slice requires the numerical solution of an eigenproblem. The slice number depends on the profile slope, i.e. the shallower it is the more slices are required. Another drawback is its slower convergence in TM-polarization, which in some cases (metals with shallow slope) may cause complete fail. Chandezon's Coordinate Transformation Method (CCM) is a viable alternative and an ideal supplement to RCWA. Both methods are modal and can be directly derived from Maxwell's equations. This talk will present a common framework for both methods based on a presentation of Maxwell's equations in general curvilinear coordinates. It combines the advantages of both methods into a powerful simulation tool for patterned multilayer samples. The derived algorithms have been implemented in the grating solver Unigit along with many other facilities to enable efficient, accurate and fast push-button grating simulations. A number of numerical and experimental examples will be presented that demonstrate the performance and the universality of the code. Finally, some suggestions will be made how non-periodic or statistical sample properties such as micro-roughness and line edge roughness could be modeled by means of this combined C-RCWA method.

38

INTERACTION OF PROTEINS WITH NANOPOROUS TITANIA SUBSTRATES Chiara Toccafondi1, 2, Ornella Cavalleri1, Emanuele Barborini3, Francesco Bisio4, Maurizio Canepa1

1 Università di Genova, Dipartimento di Fisica, Genova, Italy 2 IIT, Genova, Italy 3 THETIS-Lab, Milano, Italy 4 CNR-SPIN, Genova, Italy

canepa@fisica.unige.it The interaction of proteins with nanostructured substrates can be exploited in the design of sensitive bio-detectors for diagnostic purposes. To this aim cluster-assembled TiO2 films (20-150 nm thickness) were deposited onto silicon substrates by means of supersonic cluster beam deposition (SCBD) [1] and characterized by AFM, XPS and ellipsometry. Due to the deposition process, cluster-assembled films are intrinsically nano-granular, and show a characteristic surface roughness arising from the random stacking of spheroidal particles; further, they show high porosity at the nanoscale, with grading of pore density along the film thickness [2, 3]. Proteins of different size and different optical properties ( transparent or absorbing in the UV-VIS range) were selected and deposited on nano-granular TiO2 in order to evaluate the extent of solvent-driven penetration into the film: two relatively small proteins (lysozyme, Lys, 14 kDa, and cytochrome c, YCC, 12kDa) and a larger one, (albumin, BSA, 65 kDa). Pseudo-stratigraphic information, evaluating protein penetration inside the nano-porous structure, was obtained from in situ spectroscopic ellipsometry (SE, 245-1700 nm). Experimental data were modelled using the Effective Medium Approximation (EMA) accounting for the optical properties of the protein [4], substrate skeleton and the graded pore filling. Lys and YCC were found to reach pores located deep into the nanoporous matrix yielding similar filling fractions. On the other hand BSA was found to penetrate the substrate to a much lesser extent.

[1] Milani, P. and Iannotta, S., Cluster Beam Synthesis of Nanostructured Materials, Springer, 1999

[2] Barborini, E. et al., The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics, 24, 2003, 277-282

[3] Bisio, F. et al., Phys. Rev. B, 80, 2009, 205428 [4] Toccafondi C. et al., Journal of Colloid and Interface Science, 364, 2011, 125-132; Thin solid

films 543 2013, 78

39

IMAGING OF SURFACE IMPURITIES, IMPERFECTIONS, RESIDUES, CONTAMINATIONS AND NANO-SCALED PATTERN: MICROSCOPIC TECHNIQUES VS. ELLIPSOMETRY Uwe Beck, A. Hertwig, M. Sahre, M. Weise, J. M. Stockmann, S. Trutz BAM Federal Institute for Materials Research and Testing, Division 6.7, Unter den Eichen 87, 12205 Berlin, Germany uwe.beck@bam.de Quality control (QC) in the field of surface technology requires the fast and reliable recognition of surface impurities, imperfections, residues, contaminations and nano-scaled pattern. Atomic force microscopy (AFM) has the major advantage of both high vertical (0.1 nm) and high lateral (1 nm) resolution. However, it is a near-field technique difficult to operate under robust environmental conditions and a 3D-surface image is composed out of 2D-profiles which is time-consuming and requires a pre-scan at least for unknown, rough or topographically structured samples. Besides that, the topographic contrast is detected rather than the material contrast. Hence, AFM is usually not used for at-line QC applications. Light microscopic (LM) techniques work in the far-field and possess at-line capability. Vertical topographic features are estimated by the focal range, lateral ones can be measured down to the diffraction limit of about 0.5 µm. Material-related information may be derived from the differential inference contrast. Because of normal incidence, the entire focal plane is sharp, however no distinction can be made between p- and s-polarisation. Imaging ellipsometry is a polarisation-sensitive far-field technique at oblique incidence. Hence, only one line of the image is sharp for a given focal length. To overcome this drawback, a Scheimpflug-configuration was successfully applied. Material-related quantitative data (optical constants n and k, layer thickness d) can be retrieved from the ellipsometric quantities Ψ and Δ for the entire picture simultaneously with a vertical resolution similar to AFM, lateral comparable to LM at magnification 200. For nulling Ellipsometry close to the Brewster-angle and p-polarised incidenting light, the clean substrate becomes “invisible” in contrast to impurities or defects “as stars at the night sky”. It is shown that imaging ellipsometry has a great potential to detect hidden features by varying the P-C-A settings.

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IN-SITU IR-ELLIPSOMETRY APPLIED TO ORGANIC/SILICON INTERFACES IN SOLUTION Jörg Rappich1, Guoguang Sun2, Xin Zhang1

1 Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut für Si-Photovoltaik, Kekuléstr. 5, 12459 Berlin, Germany

2 Leibniz Institut für Analytische Wissenschaften - ISAS- e.V., Department-Berlin, Albert-Einstein-Str. 9, 12489 Berlin, Germany

Conducting and semiconducting polymers offer a unique combination of properties, which are interesting for microelectronics, sensors, and photovoltaic applications [1, 2, 3, 4, 5]. The possibility to obtain these polymers in a conducting or semiconducting state depends on the oxidation state of the respective polymer and makes these polymers to a promising material for optoelectronic applications. In-situ investigation of the growth process of such layers on silicon will be presented by following the specific vibrational signature of the structures by means of infrared spectroscopic ellipsometry (IRSE). The deposition of the layers was performed in aqueous and non-aqueous electrolyte solutions by electrochemical techniques using anodic and cathodic potential pulses. Results on the electrodeposition of polypyrrole, 4-nitrobenzene, and polyaniline will be presented and discussed in frame of the deposition conditions like applied potential, charge flow and influence of the doping molecules. Additionally, the IRSE measurements show that no (or even very small amount of) silicon oxide is formed during the deposition process on Si leading to well passivated Si/organic interfaces.

[1] N. Hall, H. Shirakawa, A. MacDiarmid, A. Heeger; Chem. Commun. 1 (2003) 1-4. [2] C. Intelmann, K. Hinrichs, V. Syritski, F. Yang, J. Rappich; Jpn. J. Appl. Phys. 47 (2008)

554-7 [3] J. Rappich and K. Hinrichs; Electrochem. Commun. 11 (2009) 2316-19 [4] G. Sun, X. Zhang, Ch. Kaspari, K. Haberland, J. Rappich, and K. Hinrichs; J. Electrochem.

Soc., 159 (2012) H811-H815 [5] J. Rappich, K. Hinrichs, G. Sun, X. Zhang in “Ellipsometry of Functional Organic Surfaces

and Films” edited by K. Hinrichs and K. J. Eichhorn, Springer Verlag 2014

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IN SITU SPECTROSCOPIC ELLIPSOMETRY - A TOOL TO STUDY “GRAFTING-ON-TOP” PROCESSES IN REACTIVE POLYMER BRUSH SYSTEMS Sebastian Rauch, K.-J. Eichhorn, M. Stamm, P. Uhlmann Technische Universität Dresden Leibniz-Institut für Polymerforschung Dresden e.V. rauch@ipfdd.de Stimuli-responsive polymer brushes are promising materials for the development of smart surfaces that can change their properties in response to environmental stimuli. The water-soluble poly(N-isopropylacrylamide) (PNiPAAm) is one of such responsive polymers with a temperature-sensitive phase transition in aqueous solution possessing a lower critical solution temperature (LCST) of ca. 31° C [1]. By introducing a second functionality at the terminal end of the brush chains it is possible to create a modular system to build up thin polymeric layers that combine a specific functionality with switchability or responsiveness. Herein we present a new functional PNiPAAm brush system which offers a reactive chain end functionality in terms of “click” chemistry [2]. In detail we (1) designed a new type of brushes by clicking a dye (Rhodamine B) to the free chain ends [3], (2) improved the thermoresponsivity in aqueous medium by the chain extension of PNiPAAm brushes and (3) introduced magnetic properties in the system by clicking functionalized Fe3O4-Nanoparticles to the free chain ends (see figure). The modified polymer brush systems were characterized ex and in situ by VIS-spectroscopic ellipsometry (SE). The experimental data were fitted with different optical models like simple box and/or generic oscillator (Gen-Osc) models, but also effective medium approaches (EMA) were applied. For the analysis of the physicochemical properties of the dye modified PNiPAAm brushes UV/VIS spectroscopy were carried out to confirm the results obtained from SE-measurements.

[1] E. Bittrich, S. Burkert, M. Müller, K.-J. Eichhorn, M. Stamm, P. Uhlmann, Langmuir 28, 3439 (2012).

[2] H. C. Kolb, M. G. Finn, K. B. Sharpless, Angew. Chem. Int. Ed. 40, 2004 (2001). [3] S. Rauch, K.-J. Eichhorn, U. Oertel, D. Kuckling, M. Stamm, P. Uhlmann, Soft Matter 8,

10260 (2012).

Modified polymer brush systems which were characterized by VIS-SE

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IN-SITU ELLIPSOMETRY STUDIES OF THIN SWOLLEN POLYMER FILMS, A REVIEW Wojciech Ogieglo1, Herbert Wormeester2, Matthias Wessling3, Nieck Benes4

1 University of Twente, Mesa + Institute for Nanotechnology, Membrane Science and Technology, P.O. Box 217 7500 , AE Enschede , The Netherlands

2 University of Twente, Mesa + Institute for Nanotechnology, Physics of Interfaces and Nanomaterials, P.O. Box 217 7500 , AE Enschede , The Netherlands

3 RWTH Aachen University, Chemical Process Engineering, Turmstrasse 46 , 52064 , Aachen , Germany

4 University of Twente , Mesa + Institute for Nanotechnology , Inorganic Membranes, P.O. Box 217 7500 , AE Enschede , The Netherlands

w.ogieglo@utwente.nl The properties of a thin polymer film can be significantly affected by the presence of the penetrant. This can have potential implications for many technological applications, such as protective and functional coatings, sensors, microelectronics, surface modification and membrane separations. In-situ ellipsometry is a powerful technique for the characterization a film in contact with a penetrant. The main advantages of ellipsometry include the very high precision and accuracy of the technique, combined with the fact that it is non-intrusive. Recent advances in the speed and automation of the technique have further expanded its application. This work provides an overview of the research that has been done by in-situ ellipsometry on penetrant-exposed polymeric films, in the last 15-20 years. The focus is predominantly on films that are not attached covalently to a substrate. The review addresses a variety of topics, covering instrumental aspects of in-situ studies, approaches to data analysis and optical models, reported precision and repeatability, the polymer-penetrant systems that have been studied, the kind of information that has been extracted, and other in-situ techniques that have been combined with ellipsometry. Various examples will be presented to illustrate different practical approaches, the consequences of the optical properties of the ambient, and the various ways that have been employed to bring polymer films in contact with a penetrant, ranging from simple ex-situ-like configurations (i.e. drying studies) to complex high pressure cells. The versatility of in-situ ellipsometry will be demonstrated by examples of the distinctive phenomena studied, such as film dilation, penetrant diffusion mechanisms, film degradation, electrochemical processes, and the broad variety of polymer penetrant systems studied (glassy and rubbery polymers, multilayer stacks, etc.). An outlook will be given on possible future trends.

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REFLECTANCE DIFFERENCE SPECTROSCOPY – A VERSATILE TOOL FOR SURFACE SCIENCE Lidong Sun Johannes-Kepler Universität Linz Institut für Experimentalphysik, Altenbergerstr.69, 4040 Linz, Austria lidong.sun@jku.at Reflectance difference spectroscopy (RDS) measures the difference of the normal-incidence optical reflectance for two mutually perpendicular orientations of the polarization vector as a function of the photon energy [1]. For cubic crystals, the optical response from the bulk is isotropic and the RDS signal arises only from the surface induced optical anisotropy. This makes RDS a highly surface sensitive optical probe, providing information on the surface structure, morphology, and electronic properties [2]. We have applied RDS to study molecular adsorption and thin film growth on metal surfaces. The presence of delocalized surface states on metal surfaces makes RDS an extremely sensitive tool for studying adsorption kinetics and ordering phenomena [3]. On the other hand, bulk derived contributions to the optical anisotropy are sensitive to surface/interface stress and can thus be used to characterize the growth mode and morphological changes of thin metal films through the associated characteristic strain/stress variations [4]. Finally, we demonstrate that apart from it sensitivity to the intrinsic optical anisotropy of the substrate, extrinsic optical anisotropy arising from the intramolecular optical transition of conjugated organic molecules is particularly strong and senses not only the orientation but also the interaction and conformation of the organic molecules contained in the growing films [5]. The enhanced sensitivity originates from the highly anisotropic molecular electronic structure as well as the anisotropic molecular interactions leading to a detection limit of the adsorbed organic molecules well below 1% of a monolayer. Study the evolution of RD signals during deposition leads to a deep understanding of the kinetics of adsorption and growth of organic thin films.

[1] D. E. Aspnes and A. A. Studna, Phys. Rev. Lett. 54, 1956 (1985). [2] P. Weightmann, D. S. Martin, R. J. Cole, T. Farrell, Rep. Prog. Phys. 68, 3043 (2005). [3] L. D. Sun, M. Hohage, P. Zeppenfeld, R. E. Balderas-Navarro, K. Hingerl, Phys. Rev. Lett. 90

106104 (2003). [4] L. D. Sun, M. Hohage, P. Zeppenfeld, R. E. Balderas-Navarro, K. Hingerl, Phys. Rev. Lett. 96

016105 (2006). [5] L. D.Sun, J. Gall, G. Weidlinger, C. Y. Liu, M. Denk, P. Zeppenfeld, Phys. Rev. Lett. 110,

106101 (2013).

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ELLIPSOMETRIC SPECTROELECTROCHEMISTRY – AN INSIGHT IN THE OPTICAL PROPERTIES OF DOPED ORGANIC SEMICONDUCTORS Jacek Gasiorowski1, Christoph Cobet1, Kerstin Oppelt2, Kurt Hingerl1

1 Center for Surface and Nanoanalytics 2 Johannes Kepler University, Institute of Inorganic Chemistry , Altenberger Str. 69, 4040, Linz,

Austria jacek.gasiorowski@jku.at The field of conducting polymers made remarkable progress in recent years. To increase applicability in organic electronics new generations of solution processable materials were developed. Usually the spectroscopic analysis is performed either in the UV-Vis or in the IR regions and based on transmission / reflection (T, R) measurements. Both methods are rather insensitive for accurate determination of the optical properties of thin layers, because the measured real quantities T and R are dominated by the reflection at the substrate boundaries. In order to assign physical properties of the pristine polymer and changes caused by doping, the variation of the complex dielectric function, can be measured much more precisely using ellipsometry. Accordingly we present an application of NIR-UV-Vis ellipsometry in spectroelectrochemical studies. A special setup was used in the UV-Vis spectral range allowing transmission ellipsometric studies during electrochemical measurement. In the system a semiconducting polymer, poly(3-hexylthiophene), the model donor material for organic solar cells, deposited on ITO/glass was used as working electrode. 0.1 M tetra(n-butyl)ammonium hexafluorophosphate in propylene carbonate was used as electrolyte solution and Pt was used as counter electrode. The ellipsometric values ψ and Δ were measured as a function of the applied potential. The obtained data were modeled and the the real and imaginary part of the dielectric function , or equivalently, the refractive index were determined for different potentials applied in the electrochemical experiment. Upon electrochemical doping, the appearance of new peaks at lower energy due to transitions in the gap is clearly resolved. In parallel, a clear variation of the P3HT thickness was found as a function of applied potential during electrochemical measurement. Moreover, ellipsometric results obtained from electrochemical studies during chemical doping in iodine vapor show fully consistent results.

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HUMIDITY EFFECTS ON FUNCTIONAL POLYMER FILMS Andreas Furchner 1, Annika Kroning 1, Sebastian Rauch2, Karsten Hinrichs1

1 Leibniz-Institut für Analytische Wissenschaften – ISAS – e. V., Dresden, Germany 2 Leibniz-Institut für Polymerforschung Dresden e. V., Dresden, Germany

andreas.furchner@isas.de Infrared ellipsometry and in-situ infrared microscopy were utilized to investigate humidity effects on swellable functional polymer films made from poly(N-isopropylacrylamide). These types of films are highly interesting for technological and bioapplications, ranging from controlled wettability to temperature-sensitive cell adhesion. The films were first characterized in dry state. Ellipsometric modeling allowed to extract the optical constants n and k, which reflect different polymer–polymer interactions. By means of infrared microscopy, the polymer films were then analyzed in-situ under controlled conditions between 0% and 35% humidity. Additional polymer–water interactions were identified within effective-medium models.

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PHONON MODE BEHAVIOR AND FREE-CHARGE CARRIER PARAMETERS IN HIGH-AL CONTENT AlGaN DETERMINED BY IR SPECTROSCOPIC ELLIPSOMETRY AND OPTICAL HALL EFFECT Stefan Schöche1, P. Kühne1, T. Hofmann1, M. Schubert1, D. Nilsson2, A. Kakanakova-Georgieva2, E. Janzén2, Vanya Darakchieva2

1 University of Nebraska-Lincoln, Department of Electrical Engineering and CNFM, Lincoln, Nebraska, 68588-0511, USA

2 Linköping University, Department of Physics, Chemistry and Biology (IFM), Linköping, 581 83, Sweden

schoeche@huskers.unl.edu Ternary alloys of AlGaN with high molar fraction of Al are of high importance as active layers in optical devices operated in the deep ultraviolet spectral. Prediction of device functionality and optimization of performance requires knowledge of the basic electronic properties of the material, including the effective mass parameter. Standard optical and electrical characterization methods are impeded by the high band gap energy and problematic fabrication of ohmic contact in these materials. Spectroscopic ellipsometry and optical Hall-effect measurements in the mid-IR spectral range allow for contact-less characterization of the anisotropic phonon mode behavior and free-charge carrier parameters in high-Al content AlGaN alloys. A set of high-quality Si-doped Al1-xGaxN films with molar fractions of Ga in the range x = 0…30% were grown by MOCVD on strain engineered AlGaN/AlN/SiC substrate structures. From the Mid-IR spectroscopic ellipsometry data, systematic shifts in the phonon mode positions are detected and the two-mode behavior of the E1(TO) mode and one-mode behavior of the A1(LO) mode found in earlier Raman studies is confirmed. The obtained dielectric function data is used as input for the analysis of optical Hall effect data taken on highly doped samples of x = 28%, x = 23% and x = 11%. A vanishing anisotropy of the effective electron mass is found with an average value of m* = 0.336 for x = 28%. Linear extrapolation by using the determined values of the effective mass and the previously reported value for GaN allows for prediction of the effective mass value for AlN. Analysis of a set of samples of similar Si concentration and varied molar Ga fraction x, shows a systematic decrease in the resulting free-charge carrier concentrations and increasing mobility parameters with decreasing Ga concentration.

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POLARIZATION RESOLVED MEASUREMENTS WITH THE NEW EUV ELLIPSOMETER OF PTB Victor Soltwisch and Frank Scholze Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587 Berlin frank.scholze@ptb.de After having developed metrology with synchrotron radiation at the storage rings BESSY I and BESSY II for more than 25 years [1], PTB extended its capabilities for EUV metrology with respect to polarization resolved measurements, particularly in the spectral region around 13.5 nm (EUV) which is going to be used for semiconductor lithography. With the development of larger numerical aperture optics for EUV and advanced illumination concepts for lithographic imaging, the polarization performance of the optical elements becomes ever more important. At PTB, we use monochromatized bending magnet radiation for the characterization of the optical elements because of the superior temporal stability and rapid tuneability of the wavelength. Thus the polarization of the radiation is almost linear, depending on the vertical beamline acceptance angle, and cannot be manipulated. Therefore, we decided to equip the soft X-ray beamline which delivers particularly well collimated and highly linearly polarized radiation with a sample manipulator which allows freely setting the orientation of the plane of deflection. Thus we are able to characterize samples in any orientation with respect to the linear polarized direction. We additionally can add a linear polarization analyzer working with a Brewster reflector to analyze the state of polarization of the reflected beam. We present first results on the polarization properties of EUV multilayer mirrors close to the Brewster angle where polarization selectivity up to several hundred is predicted from model calculations.

[1] B. Beckhoff, et al.; Phys. Status Solidi B 246, 1415-1434 (2009)

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PROBING OF THE Cu(110) SURFACE IN ELECTROLYTE BY IN-SITU SPECTROSCOPIC ELLIPSOMETRY, RAS AND STM Christoph Cobet, Gh. Barati, V. Solokha, K. Hingerl Johannes Kepler University Linz, Center of Surface and Nanoanalytics, Altenberger Str. 69, 4040 Linz, Austria christoph.cobet@jku.at

A prototype for surface oxidation processes on metals is the adsorption of halogens and especially of chloride on copper. Such processes are investigated under ultra-high vacuum conditions as well as in electrolytic reactions since many years. However, atomistic models for the first (sub-) monolayer oxidation were obtained initially only for vacuum conditions. Here, surface sensitive methods like scanning tunneling microscopy (STM), low energy electron diffraction or photo-electron spectroscopy and the feedback from ab-initio model-calculations contribute mainly to the success. Much less is known about the respective surfaces in electrolytic reactions due to the restriction of the latter methods to vacuum conditions. More recently, it was demonstrated that STM can provide atomic resolution also in electrolytes. Thus it was possible to resolve e.g. a self-organized Cl-reconstruction on Cu(100) in a HCl solution under respective electrochemical potentials. On the other hand it is known that also optical methods can be applied in different environments including liquids. We used spectroscopic ellipsometry and reflection anisotropy spectroscopy (RAS) together with a home-made electrochemical-STM in order to study in-situ the dynamics of reaction processes on the more open and unstable Cu(110) surface upon Cl absorption under varying electrochemical potentials. In 10 mM HCl solution a clean copper surface is observed at potentials below -400 mV (vs. Ag/AgCl). At less negative potentials chloride anions absorb. It will be shown that the Cu(110) surface possesses a stepwise reconfiguration which ends finally in a faceting of the complete surface. The whole adsorption/desorption process is reversible and can be clearly traced in the optical response. It will be also shown that the optically measured surface anisotropy changes with the electrochemical potential even at the pristine surface as a consequence of the changing electric field in the Helmholtz double layer.

STM images (88 nm × 88 nm) of a Cu(110) surface in 10 mM HCl at working electrode potentials of (a) -500 mV and (b) -450 mV

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FROM QCMD-ELLIPSOMETRY COMBINATION TO BIRE-FRINGENCE IMAGING CHROMATOGRAPHY AND BIRE-FRINGENCE MICROSCOPY USING SCULPTURED CO-LUMNAR THIN FILMS Mathias Schubert University of Nebraska-Lincoln, Center for Nanohybrid Functional Materials, USA schubert@engr.unl.edu In this presentation I will speak about highly-ordered three-dimensional (Sculptured) Columnar nanostructure Thin Films (SCTFs), and how SCTFs can be grown and subsequently functionalized for use in chromatography and microscopy, for example. I will show why and how such functionalized SCTFs possess a vast number of new physical, chemical and biological properties. I will discuss why Generalized Ellipsometry is the most convenient and adequate technique for optical characterization of SCTFs, and how this concept and our findings lead to new instrumentation and methodology: Bire-fringence Imaging Chromatography and Birefringence Imaging Microscopy. I will further discuss sensitivity limits to target material adsorption within SCTF monitored by Generalized Ellipsometry, and present new findings about three-dimensional plasmonic properties that provide unperceived sen-sitivity in optical detection of biofilm formation onto surfaces. I will further discuss how SCTFs inter-act with liquid ambient upon our newly developed isotope exchange method, and why Quartz Crystal Microbalance cannot be readily used for biomaterial adsorption characterization using SCTFs.

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ELLIPSOMETRIC EVALUATION OF UNINTENTIONAL SURFACE LAYERS AND ITS INFLUENCE ON GRATING RECONSTRUCTION IN COHERENT FOURIER SCATTEROMETRY Nitish Kumar1, P. Petrik1, 2, S. F. Pereira1, H. P. Urbach1

1 Delft University of Technology, Faculty of Applied Sciences, Imaging Science and Technology, Optics Research Group, P. O. Box 5046, 2600GA Delft, The Netherlands

2 Hungarian Academy of Sciences, Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences, H-1121 Budapest, Konkoly Thege Miklós út 29-33, Hungary

N.Nitishkumar-1@tudelft.nl Solving inverse problems in grating reconstruction has attracted immense attention for its applicability in various fields, most importantly in the semiconductor industry. For this application high sensitivity, repeatability, high speed, non-destructiveness and high accuracy are desired. In coherent Fourier scatterometry, a tightly focused spot interacts with the grating and the far field diffraction pattern is recorded. The diffraction efficiency of the propagating orders depends nonlinearly on the material and shape parameters of the grating. The shape parameters are then determined inversely from the far field intensity. When the feature size of the grating is in few tens of nanometer range, then any unwanted surface layer of few nm on the grating is expected to affect the far field intensity maps. Assuming that the distribution of the surface layers (for example: native silicon oxide, contamination and traces of resist removal) are identical on the wafer area with and without the structure, the effect of the thickness of oxide layer on the Si etched grating can be studied and investigated using inverse grating reconstruction. In the figure, difference in the far field intensity maps of the grating structure with (IOxide) and without (Iref) an oxide layer are shown. The incident light is TM polarized above the microscope objective and the output is a mixed (TE and TM) signal. The effect of the oxide layer thickness is presented for the grating with height variations from 40 nm to 80 nm (without oxide), while the oxide layer itself is varied from 0 to 13 nm on the structure. The forward simulations have been performed by rigorous coupled wave analysis. Optical properties of the surface overlayers are measured by ellipsometry and the error, accuracy and sensitivity of grating parameters reconstruction in presence of oxide layer will be presented.

[1] N Kumar et al., Proc. SPIE, 8324:83240Q, 2012.

The figure above represents the difference between far field intensity maps for grating with and without oxide layer on it. The nominal height of the grating is varied from 40 nm to 80 nm and the change in far field is studied for oxide layer thickness up to 13 nm. The final reconstruction of the grating shape parameters depend non-linearly on the far field. Incident polarization is TM above MO.

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DEEP ULTRAVIOLET PLASMONICS IN ALUMINUM NANOPARTICLE ARRAYS Francesco Bisio1, G. Maidecchi2, G. Gonella3, R. Moroni1, A. Giglia4, S. Nannarone5, L. Mattera2, M. Canepa2

1 CNR-SPIN, Genova, Italy 2 Unige, Genova, Italy 3 U-Temple, Philadelphia, USA 4 CNR-IOM, Trieste, Italy 5 Uni-MoRe, Modena, Italy

francesco.bisio@spin.cnr.it Aluminum nanoparticles (NPs) have long been strong candidates for ushering plasmonics in the deep-ultraviolet (DUV) spectral range. Achieving this would have important fallouts in the fields of ultraviolet non-linear optical spectroscopies and high-sensitivity biosensing. Although theoretical calculations show that Al NPs can exhibit a localized surface plasmon resonance (L-SPR) in the DUV range, the metal’s reactivity and the difficulties in sythesizing ultrafine particles have strongly hampered the research in this direction. Employing a strict control of the fabrication process conditions, we recently suceeded in realizing 2-dimensional arrays of Al NPs characterized by L-SPR well within the DUV range. The arrays consist of ensembles of ellipsoidal aluminum nanoparticles, either metalic or in an Al2O3/Al core-shell architecture, aligned along nanometric grooves of a nanopatterned LiF surface. Atomic-force microscopy showed that the NPs are ordered over large areas and exhibit a coherently-aligned ellipsoidal shape with narrow size distribution in the few tens-of-nm range. High-resolution X-ray photoemission allowed to assess the metal/oxide fraction in the nanoparticles. Polarized-light extinction measurements in the 3-12 eV range performed by synchrotron light at BEAR beamline at Elettra (Trieste) revealed the presence of the L-SPR at frequencies as high as 6.8 eV, one of the highest energies ever reported in NPs by an optical spectroscopy. The experimental data are successfully compared with theoretical calculations for the L-SPR, highlighting the contribution of different plasmon modes to the optical response.

Top: schematic representation of the optical transmission geometry. Bottom left: optical extinction of the Al/LiF NP array in longitudinal and transverse geometries (open and full markers, respectively). Bottom right: FIT calculated extinction spectra.

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OPTICAL CHARACTERIZATION OF HIGHLY INHOMOGENEOUS THIN FILMS Dana Rosu1, Andreas Hertwig1, Uwe Beck1, Peter Petrik2

1 BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12200 Berlin, Germany

2 Research Centre for Natural Sciences – Institute for Technical Physics and Materials Science, Konkoly Thege Rd. 29-33, 1121 Budapest, Hungary

dana-maria.rosu@bam.de Maintaining a consistent product quality is one of the primary concerns of the electronic industry nowadays. Therefore the development of techniques for the detection of variations and/or defects of the devices is essential. Lithographically non-ideal patterned photoresist layers were investigated using spectroscopic ellipsometry in the visible spectral range. On a larger lateral scale of several mm lateral resolution, the long range homogeneity of the sample was investigated using a goniospectral rotating compensator ellipsometer (RCE). A nulling imaging ellipsometer was used to determine the properties and the local homogeneity of the sample on a smaller scale of 25 – 150 µm. It could be shown that imaging ellipsometry delivers accurate results down to the lateral resolution limit of the method. Distributions of thicknesses of layers can be obtained even from complex layer materials with multispectral imaging ellipsometry. This method is an example of a multidimensional measurement, as the thickness is determined for every pixel of a data cube.

Thickness distribution of a photoresist layer obtained with a resolution of sub-10 µm using imaging ellipsometry

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POLARIZED SPECTROSCOPY OF METAL NANOPARTICLE FILMS AND METAMATERIALS Thomas W. H. Oates Leibniz-Institut für Analytische Wissenschaften - ISAS-e.V. Berlin tom.oates@isas.de In the electric field of a photon, the free-electrons in a conductor resonate collectively, a quantum of which is a plasmon. Plasmonic resonances in metallic nanoparticles are used to enhance Infrared and Raman cross-sections and also photovoltaic and LED efficiency. They are also the basis of mesoscopic "artificial atoms" used in metamaterials to demonstrate artificial magnetism and negative refractive index. With the correct models, spectroscopic ellipsometry allows the simultaneous determination of the nanoscale structural and macroscopic optical properties of such materials. The slab (thin film) models of traditional ellipsometry require refinement using effective medium models and concepts to account for the spherical and vertical boundaries now present in the material. For metal structures that are uniaxial or biaxial anisotropic, refinements to the effective medium approximations must be made. When the dimensions of the structures are not significantly smaller than the exciting wavelength, the dipole assumption used ubiquitously in optics begins to lose its validity. In this case we may retain the simplicity of the thin film model only if the effects of higher order multipoles are explicitly included into the constituent dielectric functions. This provides a theoretical explanation for the effective magnetism observed in plasmonic metamaterials. It is also used in some cases to describe “extrinsic chirality” in metamaterials with low-symmetry. When the dimensions of the metal structures are of the order of the wavelength, the thin film models are no longer useful and computationally-intensive Maxwell-solvers are required. These are numerous in theory and practice and are continually improving in speed and accuracy. The integration of these with ellipsometric measurements bridges the gap between ellipsometry and scatterometry and provides exciting potential for new fields of application.

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POLARIZING NATURAL CHIRAL NANOSTRUCTURES Kenneth Järrendahl Linköping University, Department of Physics, Chemistry and Biology, SE-58183 Linköping, Sweden kejar@ifm.liu.se Light in the natural environment is often polarized to some extent. This includes skylight, underwater light and light from surface reflections. Linear polarization is by far most common even though other polarization states are observed. The human eye is, in principle, polarization blind but many living species have polarization vision and can benefit from the polarization patterns in nature. Polarized light can also be generated from animals and plants. In many cases this is due to surface reflections near the Brewster angle or from structured materials but there are also examples of emission of polarized light. After a brief overview on polarization in nature including the animal phyla Arthropoda, Chordata and Mollusca, the presentation will be focused on chiral chitin structures. Chitin is a common component in animal anatomy, often in a twisted and therefore chiral arrangement. In many cases this causes reflections from these structures to be elliptically or circularly polarized. In this work, chiral chitin nanostructures in the exoskeletons of scarab beetles are of special interest. Mueller-matrix spectroscopic ellipsometry measurements were performed on several beetles from the Scarabaeoidea subfamilies Cetoniinae and Rutelinae with a dual rotating compensator ellipsometer. Full Mueller matrix data were recorded as a function of wavelength λ ϵ [245, 1000] nm, incident angle θ ϵ [20, 75]º and sample orientation φ. Among many interesting optical features it is observed that the studied beetle structures reflect light with a high degree of circular polarization Pc in certain λθ-regions. Fresnel-based simulations of the optical response from twisted chitin structures were performed giving the Mueller matrix as a function of λ, θ and φ. The simulated data corresponds well to the measured data. Subsequent regression analysis gives more detailed information on the beetle exoskeletons and makes it possible to specify trends and differences among the observed beetle species.

Pseudochalcothea auripes

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ELLIPSOMETRIC STUDY OF ZnFe2O4, CoFe2O4, AND ZnCo2O4 SPINEL OXIDES Vitaly Zviagin¹, P. Richter², T. Böntgen¹, M. Lorenz¹, D. R. T. Zahn², G. Salvan², R. Schmidt-Grund¹, M. Grundmann¹

1 Universität Leipzig, Institut für Experimentelle Physik, II, Linnéstr. 5, D-04103 Leipzig, Germany

2 Chemnitz University of Technology, Semiconductor Physics, Reichenhainer Str. 70, D-09126 Chemnitz, Germany.

pge09jgk@studserv.uni-leipzig.de Spinel oxides have been of interest due to their potential use in data storage, information processing, and spintronic devices [1]. We present a study of (magneto-) optical properties of PLD grown ZnFe2O4, CoFe2O4 and ZnCo2O4 thin films on MgO substrates. We applied ellipsometry in the spectral range 0.5 – 9 eV and at temperatures 10 – 300 K. Using a series of model dielectric functions we develop a parametric model for the dielectric function of the thin films, derive transition energies, and give an explanation for the origin of observed transitions. We furthermore show the temperature dependence of these transitions and give an explanation for the behavior observed. We present the magneto-optical response of the dielectric tensor using magneto-optical Kerr effect spectroscopy. The optical properties of most spinel oxides in the visible spectral range up to ~6 eV are dominated by charge transfer transitions connected to metal ion 3d orbitals. A manyfold of these transitions occur either between transition metal ions (in different sublattices or oxidation states) or between metal ions and oxygen atoms, forming broad absorption bands of overlapping transitions, with weak crystal field transitions superimposed on this. For ZnFe2O4 the dielectric function is dominated by charge transfer transition from O2p to Fe3d at ~3 eV, followed by a strong O2p to Fe4s transition at ~6 eV. In contrast, CoFe2O4 dielectric model contains dominating charge transfer transitions from O2p to Fe3d above ~3 eV and metal d to d on-site transitions below [2]. Due to high degree of inversion present in the ZnCo2O4 thin films, additional transitions below the fundamental charge transfer transition at 2.3 eV are present. The study of optical properties is accompanied by structural analysis of the thin films using atomic force microscopy, and X-ray diffraction.

[1] M. Opel et al., phys status solidi A 208, 232 (2011). [2] C. Himcinschi et al., J. Appl. Phys., 113, 084101 (2013).

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MUELLER MATRIX CHARACTERIZATION OF PLASMONIC MEANDERS Audrey Berrier1, 3, Bruno Gompf1, 3, Liwei Fu2, 3, Thomas Weiss1, 3, Heinz Schweizer1, 3

1 Universität Stuttgart, Physikalisches Institut, Pfaffenwaldring 57, 70550 Stuttgart, Germany 2 Universität Stuttgart, Institut für Technische Optik, Pfaffenwaldring 9, 70550 Stuttgart,

Germany 3 Universität Stuttgart, Research Center SCoPE, Germany

audrey.berrier@pi1.physik.uni-stuttgart.de We present the design, fabrication and optical characterization of a plasmonic meander with extraordinary optical properties. The meander consists of a thin (40 nm) layer of a corrugated Ag film deposited on periodic MgF2 ridges. This structure has a rich dispersion, which is induced by the coupling of the short-range and long-range surface plasmon polaritons (SPP) modes. The dispersion can be tuned by the geometrical parameters of the structure. The controlled coupling of the two SPP modes results in an enhanced transmission passband, and a large phase retardation between s- and p-polarized light is expected, leading to a large polarization conversion. At resonance, a large phase shift is usually related to a strong absorption. By proper design, the interference of the two SPP modes slightly detuned in frequency creates a region with a large phase shift where absorption is suppressed, like in the case of the present meander. Along with transmission measurements to determine the dispersion of the modes at play, we perform Mueller Matrix (MM) spectroscopy to obtain phase information. The measured MM elements are compared with calculations. It is here intended to analyse the complete Mueller matrix of the meander structure beyond simple spectral measurements to obtain the full amplitude and phase response of the metamaterial over a large frequency range and in a broad k-space. The structure presents a particularly large phase retardance and a huge optical rotatory power, several orders of magnitude larger than that observed in conventional crystals, although it is extremely thin. The applications range from subwavelength imaging and superlensing to polarization scramblers for space applications. This study presents the experimental demonstration of the outstanding properties of the Ag meander, brings a novel understanding of the interaction of the plasmonic structure with polarized light, and opens the path for future designs with respect to plasmonic integration.

(left) Schematic drawing of the fabricated silver meander structure; (right) Calculated dispersion plot displaying the transmission band as well as the contributions of the long range (LR) and short range (SR) surface plasmon polaritons.

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EXPANDED BEAM SPECTROSCOPIC ELLIPSOMETRY FOR THIN FILM SOLAR CELL PRODUCTION Miklós Fried Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences (MTA TTK MFA), H-1525 Budapest, POB 49, Hungary fried@mfa.kfki.hu Non-destructive analysis tools are needed at all stages of thin film process-development, especially photovoltaic (PV) development, and on production lines. In the case of thin films, layer thicknesses, micro-structure, composition, layer optical properties, and their uniformity are important parameters. An important focus is to express the dielectric functions of each component material in terms of a handful of wavelength independent parameters whose variation can cover all process variants of that material. With the resulting database, spectroscopic ellipsometry (SE) coupled with multilayer analysis can be developed for on-line point-by-point mapping and on-line line-by-line imaging. This talk will try to review the investigations of different types of PV-layers (anti-reflective coating, transparent-conductive oxide (TCO), multi-diode-structure, absorber and window layers) showing the existing dielectric function databases for the thin film components of CdTe, CIGS, thin Si, and TCO layers. Off-line point-by-point mapping can be effective for characterization of non-uniformities in full scale PV panels in developing labs but it is slow in the on-line mode when only 15 points can be obtained (within 1 min) as a 120 cm long panel moves by the mapping station. Last year [1, 2], a new instrumentation was developed that provides a line image of SE (λ = 350-1000 nm) data. Earlier a single 30 point line image could be collected in 10 s over a 15 cm width of PV material [3, 4]. These years we are building a 30 and a 60 cm width expanded beam SE which speed will be increased by 10 X. Then 1800 points could be mapped in a 1 min traverse of a 60*120 cm PV panel or flexible roll-to-roll substrate. Another enhancement is the switch-over to rotating compensator measuring principle.

[1] C. Major et al., PSS (c), 5, 1077, 2008 [2] G. Juhász et al., PSS(c), 5, 1081, 2008 [3] M. Fried et al., TSF 519, 2730, 2011 [4] M. Fried et al., MRS Proc. v1323, DOI: 10.1557/opl.2011.820. 2011

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IN LINE MONITORING OF POLYCRYSTALLINE SILICON FORMATION BY SPRAY COATING AND FLASH LAMP ANNEALING OF SILICON NANOPARTICLE SUSPENSIONS Falko Seidel1, Ovidiu D. Gordan1, Ronny Fritzsche2, Benjamin Büchter2, Alexander Jakob3, Roy Buschbeck3, Hans Freitag1, Andreas Liebig4, Michael Hietschold5, Manfred Albrecht4, Heinrich Lang3, Michael Mehring2, Dietrich R. T. Zahn1

1 Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz, Germany Coordination Chemistry, D-09107 Chemnitz, Germany

2 Chemnitz University of Technology, Inorganic Chemistry, D-09107 Chemnitz, Germany 3 Chemnitz University of Technology, Surface and Interface Physics, D-09107 Chemnitz,

Germany 4 Chemnitz University of Technology, Solid Surface Analysis, Chemnitz, D-09107 Chemnitz,

Germany falko.seidel@physik.tu-chemnitz.de This work presents a novel method for obtaining thin polycrystalline silicon films from spray coated silicon nanoparticle (Si NP) suspensions. The samples are prepared under nitrogen atmosphere in a glove box to prevent oxidation. A mixture of Si NP with organosilicon compounds is sprayed onto molybdenum substrates. The organosilicon facilitates a homogeneous film deposition by interconnecting the Si NP. In a following step the spray coated silicon films are treated via flash lamp annealing (FLA). An in line spectroscopic ellipsometer - attached to the glove box - enables to watch in real time the preparation steps. The critical points of crystalline silicon are visible in the effective dielectric function of such FLA treated silicon films (see figure). The modeling of the ellipsometric data was possible using the effective medium approximation (EMA) consisting of 53% crystalline, 33% amorphous, and 14% oxidized fractions of silicon as shown in Figure 1. Furthermore, micrometer thin silicon foils are exfoliated and investigated with complementary techniques such as X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. All techniques independently indicate the presence of polycrystalline silicon. This result is an example of the powerful ability of in line spectroscopic ellipsometry as a real time characterization technique.

Spectroscopic ellipsometry of pristine spray coated Si NP and flash lamp annealed (FLA) Si films. Typical transitions of crystalline silicon are visible at around E1 = 3.4 eV and E2 = 4.2 eV.

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OPTICAL PROPERTIES AND QUALITY OF ROLL-TO-ROLL PRINTED NANOLAYERS FOR ORGANIC PHOTOVOLTAICS BY IN-LINE SPECTROSCOPIC ELLIPSOMETRY Argiris Laskarakis1, D. Georgiou1, Ch. Kapnopoulos1, C. Koidis2, G. Antonopoulos2, S. Logothetidis1

1 Aristotle University of Thessaloniki, Department of Physics, Nanosystems & Nanometrology (LTFN Lab for Thin Films,), 54124 Thessaloniki, Greece

2 Organic Electronic Technologies P.C., Antoni Tritsi 21B 57001, Thessaloniki, Greece alask@physics.auth.gr Organic electronics (OE) is a rapidly growing field that provides low-cost and flexible electronics due to the capability for printing of OE nanolayers by roll-to-roll (r2r) processes. The OE applications include organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), organic thin film transistors (OTFTs), sensors, biosensors, etc. However, the insufficient process optimization results to undesirable fluctuations in the micro-structure and thickness of the r2r printed nanolayers, and consequently to OE devices with limited perfor-mance and lifetime. The in-situ monitoring and quality control has a significant importance for the optimization of the r2r process and it will ensure the development and optimization of OE nanolayers and devices with the desired performance and lifetime. In this work, we discuss the real-time monitoring and analysis of optical properties and nano-scale morphology of r2r gravure printed nanolayers for OPVs onto flexible substrates by in-line SE in the visible-far ultraviolet spectral region. These nanolayers include barrier layers, Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) transparent electrodes and poly(3-hexylthiophene):(6,6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM) bulk heterojunction (BHJ) blends. The capability for scanning in both machine and transverse directions ensures the accurate mapping of the film thickness and optical properties over the whole running polymer web surface. Also, we discuss on the effect of the experimental process parameters on the thickness and the morphology of the BHJ blends during the web rolling. The proposed methodology opens the way for the in-line robust determination of the optical properties and quality of other nanolayers for several OE applications (e.g. OLEDs, OTFTs, sensors, and biosensors). Finally, it emphasizes the potentiality of in-line SE to become a standard technique for the r2r manufacturing of flexible OE materials and devices.

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FOURIER ELLIPSOMETRY – AN ELLIPSOMETRIC APPROACH TO FOURIER SCATTEROMETRY Peter Petrik1, 2, N. Kumar1, B. Fodor2, 3, S. F. Pereira1, M. Fried2, H. P. Urbach1

1 Delft University of Technology, Faculty of Applied Sciences, Department of Imaging Science and Technology, Optics Research Group, P. O. Box 5046, 2600GA Delft, The Netherlands

2 Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute for Technical Physics and Materials Science, H-1121 Budapest, Konkoly Thege Miklós út 29-33, Hungary

3 University of Pécs, Faculty of Science, 7624 Pécs, Ifjúság útja 6, Hungary p.petrik@tudelft.nl Optical scatterometry is used in numerous configurations from monochromatic to spectroscopic, from reflectometric to polarimetric, from specular to angle resolved, from coherent to incoherent. In coherent Fourier scatterometry (CFS) a micrometer-size focused spot is created by a high numerical aperture (NA) microscope objective (MO), and the scattered illumination is collected by the same MO. In this configuration, each point of the back focal plane of the MO is uniquely related to a given reflection and azimuth angle. CFS allows the measurement of small and weakly reflecting samples over a wide range of reflecting angles. Using high NA MOs the angles of reflection cover the range from 0 to over 70° (72° for NA = 0.95), and the distance of the objective is only several hundred wavelengths from the sample surface. The whole back focal plane image that includes the response of the sample at all azimuth angles can be recorded within less than a second. By scanning the focused spot, the phase can be modulated and the phase difference between the overlapping orders can be determined resulting in an increase in the sensitivity by a factor of ≈3 as compared to phase-insensitive incoherent Fourier scatterometry. The performance of CFS can further be increased by combining it with interferometry or ellipsometry. Using interferometry, the complete scattering matrix can be evaluated. The absolute phase of the diffracted orders can be retrieved using a known reference beam. The ellipsometric approach can be considered as a variant of the interferometric method, in which the reference beam for one polarization is that of the orthogonal polarization with regard to the plane of incidence. Our presentation will discuss the ellipsometric approach and the possibilities to combine it with the current CFS metrology.

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SETTING UP A METROLOGICAL TRACEABLE MUELLER POLARIMETER Poul-Erik Hansen and Lars Nielsen DFM A/S, Danish National Metrology Institute, Matematiktorvet 307, 2800 Kgs. Lyngby, Denmark peh@dfm.dk Ellipsometers and Mueller Polarimeters are generally recognized as valuable instruments for thickness characterization of thin film devices. However, there is an ongoing dispute about the validity of results obtained using such instruments. These lacks of confident in the obtained results using these instruments are due to the inverse nature of modeling the surface, due to the fact that these technologies measure several parameters simultaneously and due to the fact that it is only possible to calibrate the instrument using transfer standards. Here we consider the challenges, and our solutions, of making a traceable Mueller Polarimeter that does not require calibration standard(s). The topics that need to be addressed are:

• Reformulation of the ellipsometric equation in terms of direct experimental measurands such that we can associate a measurement uncertainty to each measurands

• Reformulation of the theoretical modeling such that the model parameters are linked to the experimental measured intensities and not the derived ellipsometric quantities Psi and Delta

• Make analyzing software package that fulfill the requirement in the Guide to the expression of uncertainty in measurements (GUM)

• Build a Mueller Polarimeter that can measure the complete Mueller matrix using commercial components

• Characterized all the experimental components in terms of measurands and measurement uncertainties

At the end we present some resent measurement results on SiO2 films that shows the capability of the system.

The top figure is a technical illustration of the traceable Muller Polarimeter and the bottom figure is a fit between modeled and measured intensity for a SiO2 film on silicon

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Abstracts of the posters

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P1 CHARACTERIZATION OF ANISOTROPIC PLASMONIC NANOSTRUCTURES FROM TEMPLATE-ASSISTED SELF-ASSEMBLY Christian Kuttner, Christoph Hanske, Moritz Tebbe, Andreas Fery University Bayreuth, Physical Chemistry II christian.kuttner@uni-bayreuth.de We present bottom-up assembled functional surface structures, which are promising candidates for tailoring of optical properties. Plasmonic nanoparticle arrays are excellent candidates for their potential use in optical devices such as sensors, waveguides, or photovoltaic cells. Their electromagnetic behavior is highly dependent on their specific particle size, shape, and surrounding environment. However, the lack of capability to form reproducible organized structures is still a challenge to solve in order to use these building blocks for metamaterial preparation. We developed a method to generate linear assemblies of nanoparticles in high quality and with high reproducibility by template-assisted self-assembly [1, 2, 3]. Here, wrinkled surfaces are exploited as versatile templates to self-assemble various particle types via convective flow. Subsequently, these organized particles can be transferred to solid substrates, which is a prerequisite for many technological applications. Assembly of functional nanoparticles yields optical anisotropic surface structures, which we characterized by polarized UV/VIS spectrometry and spectroscopic ellipsometry.

[1] Schweikart, A.; Fortini, A.; Wittemann, A.; Schmidt, M.; Fery, A. Nanoparticle Assembly by Confinement in Wrinkles: Experiment and Simulations. Soft Matter 2010, 6, 5860–5863.

[2] Schweikart, A.; Pazos-Perez, N.; Alvarez-Puebla, R. A.; Fery, A. Controlling Inter-Nanoparticle Coupling by Wrinkle-Assisted Assembly. Soft Matter 2011, 7, 4093–4100.

[3] Hanske, C.; Müller, M.B.; Bieber, V.; Tebbe, M.; Jessl, S.; Wittemann, A.; Fery, A. The Role of Substrate Wettability in Nanoparticle Transfer From Wrinkled Elastomers: Fundamentals and Application Towards Hierarchical Patterning. Langmuir 2012, 28, 16745–16750.

Organized transfer of gold nanoparticles onto a solid substrate by template-assisted self-assembly.

P2 SPECTROSCOPIC ELLIPSOMETRY FOR CHARACTERIZATION OF GRAPHENE OXIDE ON WAFER SURFACES Alice Kasjanow, W. M. Munief, S. Ingebrandt, P. Pokrowsky University of Applied Sciences Kaiserslautern, Campus Zweibrücken, Germany a.kasjanow@live.de 1 Introduction Graphene is a promising new material with special electrical and biocompatible properties for micro and nano technologies. In recent years, graphene and graphene oxide due to their superior characteristics were in focus of the material research especially for sensing or bioapplications [1]. Today´s handling and cost-effective processing provides many well-known advantages to apply and structure graphene on wafer level. In this work, spectroscopic ellipsometry was used for the gradual rapprochement with thin layers of graphene oxide on wafer surfaces. 2 Results and Conclusions The layer stack for the spectroscopic ellipsometry measurements is shown in the figure. For good adhesion the self-made graphene oxide flakes were applied via spin coating to a silicon wafer silanized with (3-Aminopropyl)triethoxysilane (APTES). To take into account the deviation of the coatings on the wafer surface a template were used and the thickness of the coatings were measured with spectroscopic ellipsometry in each case at the same measurement point consecutively after each coating step. Those parameters are kept constant in the model, when the spectrum on the single graphene oxide layer is fitted for thickness, refractive index and extinction of graphene oxide. For the fitting the Cauchy model was used. Another challenge was the detection of the monolayer after silanization with APTES. The partial fit makes it possible to detect successfully very thin graphene oxide layers of the self-made graphene oxide flakes with largely unknown optical properties and to determine it with high reproducibility.

[1] Geim, A. K. and K. S. Novoselov: The rise of graphene, Nature materials. 6 (3), 183-191, 2007.

Layer stack for spectroscopic ellipsometry measurements

P3 FAST VECTOR MAGNETO-OPTICAL GENERALIZED ELLIPSOMETRY N. Du1, Laveen Prabhu Selvaraj1, R. K. Sing1, R. Mattheis2, I. Skorupa1, 3, O. G. Schmidt1, 4, H. Schmidt1

1 Chemnitz University of Technology, Faculty of Electrical Engineering and Information Technology, 09107 Chemnitz, Germany

2 Institute of Photonic Technology, Albert-Einstein-Str. 9, D-07745 Jena, Germany 3 Helmholtz Research Center Dresden-Rossendorf e.V., Bautzner Landstrasse 400, 01328

Dresden, Germany 4 Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Institute for Integrative

Nanosciences, Helmholtzstraße 20, 01069 Dresden, Germany heidemarie.schmidt@etit.tu-chemnitz.de Ferromagnetic shaped nanomaterials, e.g. slanted columnar thin films [1], are interesting for magnetooptical applications since magnetic and optical properties can be tailored at the same time. The challenge is to understand the magnetic behaviour of shaped nanomaterials because the choice of external magnetic field directions in superconducting quantum interference device and magnetic force microscopy measurements is typically limited. We have setup a variable-angle vector magneto-optical generalized ellipsometer (VMOGE) using an octupole magnet and demonstrated VMOGE measurements in a magnetic field of arbitrary orientation and magnitude while the sample remains fixed and no further calibration is required [2]. Having the sample mounted on an automated rotation stage, VMOGE allows to perform field-free generalized ellipsometry measurements in order to allocate optical axes and determine optical constants which is particularly important before attempting to characterize the magnetooptical response induced by an external magnetic field [3]. Here we focus on the collaborative design and construction of the octupole magnet and the sample holder stage. During all VMOGE measurements one has to ensure that the probed sample portion is homogeneously magnetized and that the probe beam is blocked only in a small angle of incidence range. As an example we present VMOGE data of ferromagnetic thin films (Fe, Ni20Fe80, Co, Ni80Fe20, Ni) recorded with a 0.4 T octupole magnet from AMACC® and with the spectral ellipsometer VASE® in the spectral range from 300 nm to 1100 nm and with the fast spectral ellipsometer RC2® in the spectral range from 245 nm to 1000 nm. The ferromagnetic thin films were deposited on ZnO substrates and capped by a Cr layer.

[1] D. Schmidt, C. Briley, E. Schubert, M. Schubert, Appl. Phys. Lett. 102 (2013) [2] K. Mok, N. Du, H. Schmidt, Rev. Sci. Instrum. 82 (2011) [3] K. Mok, G. J. Kovács, J. McCord, L. Li, M. Helm, H. Schmidt, Phys. Rev. B 84 (2011)

P4 SPECTROSCOPIC ELLIPSOMETRY OF HIGHLY ORDERED PYROLYTIC GRAPHITE IN THE FAR INFRARED WAVELENGTH REGIME Till Mohr, W. Elsäßer Technische Universität Darmstadt, Institut für Angewandte Physik, Schloßgartenstr. 7, 64289 Darmstadt, Germany till.mohr@physik.tu-darmstadt.de In nature, carbon atoms can appear in different solid forms including diamond, graphite and amorphous carbon. Due to their different possibilities of chemical binding, they exhibit quite different mechanical, electrical and optical characteristics. Beyond this, carbon atoms can be processed into atomic monolayer films or complex structures such as nanotubes and buckyballs. In combination with metamaterials, new composite materials with tailored optical properties can be realized [1, 2]. Despite the fast progress in graphene processing, monolayer samples can exhibit partial multilayered graphene and defects. To distinguish between mono- and multilayer graphene recent investigations using ellipsometry in the visible wavelength regime showed a change in the ellipsometry angles with the number of layers [3]. In particular, multilayered graphene can exhibit misalignments between two neighboured layers, the so-called mosaic spread dominantly affecting the quality factor of highly ordered pyrolytic graphite (HOPG). Here, ellipsometry is expected to yield new insight into the influence of the mosaic spread on the complex refractive index of HOPG. For this purpose, HOPG samples with varying mosaic spreads are studied by spectroscopic ellipsometry in the far infrared wavelength regime. These investigations aim for an improved understanding of graphene and its unique optical properties and high electron mobility, which makes it suitable for a broad spectrum of applications in the terahertz regime.

[1] T. Otsuji, S. A. Boubanga Tombet, A. Satou, H. Fukidome, M. Suemitsu, E. Sano, V. Popov, M. Ryzhii, V. Ryzhii, J. Phys. D: Appl. Phys. 45 (2012)

[2] H. Yan, X. Li, B. Chandra, G. Tulevski, Y. Wu, M. Freitag, W. Zhu, P. Avouris, F. Xia, Nat. Nanotechnol. 7, 330 (2012)

[3] V. G. Kravets, A. N. Grigorenko, R. R. Nair, P. Blake, S. Anissimova, K. S. Novoselov, A. K. Geim, Phys. Rev. B 81, 155413 (2010)

P5 WIDE SPECTRAL RANGE ELLIPSOMETRIC STUDY OF NANOSTRUCTURED ITO/AG HYBRID LAYERS BY NODE SPLINE METHOD Peter Basa1, L. Makai1, A. A. Khosroabadi2, P. Gangopadhyay2, R. A. Norwood2

1 Semilab Semiconductor Physics Laboratory Co. Ltd., Budapest XI., Prielle K. u. 2. 1117, Hungary

2 The University of Arizona, College of Optical Sciences, Tucson, Arizona 85721, USA peter.basa@semilab.hu Optical characterization of metal-semiconductor nanostructures is widely studied due to their potential applications in novel optoelectronic devices. Optical plasma frequency, in particular, is a key property for such application due to its significant role in determining light confinement. Novel indium tin oxide (ITO)-Ag hybrid nanopillar structures were fabricated by deposition on nanopatterned polyacrylonitrile (PAN) atop glass substrates [1]. In this study, the optical plasmonic response of such nanostructured samples along with their planar control samples is characterized simultaneously by Infra-Red Spectroscopic Ellipsometry (IRSE) and UV-VIS-NIR Spectroscopic Ellipsometry. Optical functions of the studied materials were extracted from the measured spectra by using the so-called node method which uses a pure mathematical spline-based approach for dispersion modeling [2]. The plasmonic response is quantified by applying Drude model fit to the obtained IR absorption tail of the dielectric spectra. The obtained results show plasma frequency variation related to structural change in the material due to nanopatterning.

[1] A. A. Khosroabadi et al., Optics Letters 38 (2013) 3969. [2] J. Hazart, “Method for the optical characterization of materials without using a physical

model” Patent US 7307723 B2, 11 December 2007.

AFM image of the nanostructured ITO-Ag hybrid sample

P6 MAGNETO-OPTICAL CHARACTERIZATION OF ORGANIC/INORGANIC HETEROSTRUCTURES WITH SUB-MILLIMETER RESOLUTION Peter Richter1, Sreetama Banerjee2, Carsten Schulze3, Danny Reuter2, Karla Hiller2, Manfred Albrecht3, Dietrich R. T. Zahn1, Georgeta Salvan1

1 Chemnitz University of Technology, Semiconductor Physics, 09107 Chemnitz, Germany 2 Chemnitz University of Technology, Center for Microtechnologies (ZfM), 09107 Chemnitz,

Germany 3 Chemnitz University of Technology, Surface and Interface Physics, 09107 Chemnitz, Germany

peter.richter@physik.tu-chemnitz.de For fabricating lateral organic spintronic devices such as spin valves or spin-OFETs, we employ a trench formation technique based on conventional UV lithography and semiconductor processing, providing electrode separation gaps of less than 100 nm. As ferromagnetic electrode material, we deposit a 30 nm thick cobalt layer by electron beam evaporation, while the trenches are filled with a 300 nm thick organic film of copper phthalocyanine (CuPc) or cobalt phthalocyanine (CoPc) by means of organic molecular beam deposition. Using a newly developed setup for spatially resolved magneto-optical Kerr effect (µMOKE) spectroscopy, we investigate the heterostructure made from the cobalt electrodes and the CoPc filled trench with regard to its magneto-optically active electronic transitions (see figure). The spectra are dominated by optical interference features with unusually high intensity. Their origin lies in the enhancement of the signal of the underlying metal through interference in the organic layer. Apart from this, also the main absorption band of the organic molecules is visible at 1.9 eV (see inset). The dielectric function of the organic layer is determined by spectroscopic ellipsometry measurements and the application of a suitable optical model. For magnetic characterization, the magnetization hysteresis of the system is measured by µMOKE magnetometry in both polar and longitudinal geometry at a photon energy of 1.5 eV, revealing that the electrode magnetization lies in-plane. In addition, the domain structure of the Co electrodes was investigated by magnetic force microscopy.

Interference enhanced µMOKE spectrum of 300 nm CoPc on Co

P7 POLARIZATION OF LIGHT REFLECTED FROM CETONIINAE AND RUTELINAE BEETLES UNDER VARIOUS ILLUMINATIONS Lía Fernández del Río, H. Arwin, K. Järrendahl Linköping University, Department of Physics, Chemistry and Biology, Laboratory of Applied Optics, SE-581 83 Linköping, Sweden liafe@ifm.liu.se Many beetles in the Scarabaeidae subfamilies Cetoniinae and Rutelinae are well known for the eye-catching metallic-looking colouration of their exoskeletons, but so far it is unknown whether this colouration helps them to hide, to discourage predators or for intraspecic communication. This colouration is a structural colour originating from reflection of light on their exoskeleton. We have studied several beetles from the Cetonia, Protatetia and Chrysina genera with Mueller matrix ellipsometry (RC2, J. A. Woollam Co., Inc.). A general finding is that when illuminated with unpolarized light, the reflected light shows a high degree of left-circular polarization. For some species also right-circular polarization is observed. This is dependent on the wavelength λ and incident angle θ. Our measured data are presented in λθ-contour plots of the Mueller matrix elements as exemplified in the figure There are however several reasons for also studying cases where the incoming light is polarized as well as cases when only certain states of polarizations can be detected. For instance, the light from the sky and also in a rain-forest is polarized. Additionally, some birds and also other animals e.g. beetles have the ability to detect polarized light but often limited to some regions on the Poincaré sphere. In the latter case there has been some attempts to prove whether the scarab beetle Chrysina gloriosa (see figure) is able to distinguish circularly polarized light or not, but there are so far no conclusive results. In this work we have investigated how several species (including Cetonia aurata and Chrysina gloriosa) reflect light under illumination with various polarization states. In addition we have studied how the reflected light depends on the polarization sensitivity of the detector which may be an eye. The results are presented in λθ-contour plots of the Mueller matrix elements giving a good understanding of the different situations proposed.

A λθ-contour plot for λ = [245; 1000] nm and θ = [20; 75] degrees of the m41 element of the Mueller matrix from a measurement on Chrysina gloriosa shown in the photo.

P8 MUELLER MATRIX CHARACTERIZATION OF THREE-DIMENSIONAL GOLD NANOSTRUCTURES E. Mbekwe Pafong, Audrey Berrier, B. Gompf, B. Frank, H. Giessen, M. Dressel Universität Stuttgart, Physikalisches Institute and Research Center SCoPE, Pfaffenwaldring 57, 70550 Stuttgart audrey.berrier@pi1.physik.uni-stuttgart.de Mueller matrix (MM) spectroscopy is a powerful tool to characterize nanostructures as it provides both amplitude and phase information. The decomposition of the measured MM grants the extraction of all the optical parameters such as linear birefringence/dichroism and circular birefringence/dichroism. However, it is difficult to attribute effective parameters to artificial nanostructures, especially when they are three-dimensional (3D). A full characterization in a large frequency range and broad reciprocal space is therefore necessary. Along with angle-resolved transmission measurements to determine the spectral position and the dispersion of the resonant modes, we perform MM spectroscopy to obtain phase information and compare the optical behaviour to that of conventional crystals. The measured MM elements are compared with simulations based on general oscillator models taking into account the azimuthal and spectral positions of the resonances. We find that the 3D nanostructures exhibit a complex optical response that cannot be reproduced by basic optical properties such as birefringence or optical activity only. Spirals with different geometries are compared in order to extract the optical response intrinsic to their 3D nature. This study sheds light on the complex response of plasmonic nanostructures and is useful for future designs of novel optical devices.

a) Schematic drawing of the fabrication of the 3D nanospirals b) Measured Mueller matrix elements M10 (top) and M20 (bottom).

P9 OPTICAL AND MAGNETOOPTICAL PROPERTIES OF MAGNETOPLASMONIC STRUCTURES STUDIED BY MUELLER MATRIX ELLIPSOMETRY Lukáš Halagačka1, 2, K. Postava1, B. Dagens2, 3, F. Vaurette4, J. M. Vanvolleghem4, J. Ben Youssef5, J. Pištora1

1 Technical University Ostrava, Department of Physics and Nanotechnology Center, 17. listopadu 15, 708~33 Ostrava - Poruba, Czech Republic

2 Université Paris-Sud, Institut d'Électronique Fondamentale, 91405 Orsay, France 3 CNRS, UMR 8622, 91405 Orsay, France 4 CNRS, Institute of Electronics, Microelectronics and Nanotechnology, UMR 8520,Villeneuve

d'Ascq CEDEX, France 5 University of West Bretagne, Laboratory of Magnetism, (FRE CNRS 2697), Brest, France.

lukas.halagacka@gmail.com In this paper we present analysis of the optical and magnetooptical response of the 1-D periodic magnetoplasmonic structures. Possible tuning of the magnitude and the spectral position of maxima of the transverse magnetooptic Kerr effect (TMOKE) by the geometry of the structure is demonstrated. The magnetoplasmonic structure is a 1D periodic gold grating developed on the magnetooptical garnet substrate. The structure itself supports two types of resonant modes: the surface plasmon modes and the cavity modes [1]. Following our recent theoretical results [2, 3], we experimentally demonstrate that the interaction of resonant modes in the structure directly affects nonreciprocal optical response. Dual rotating compensator Mueller matrix ellipsometer is used for the optical characterization in a spectral range from 0.74 eV to 6.42 eV and in a range of incident angles from 20° to 60°. To determine magnetooptical activity the ellipsometric setup is extended with the in-plane permanent magnet circuit. Measuring the dispersion of the resonances by varying the incidence angle of the spectroscopic magnetooptical ellipsometer has allowed us to determine precisely the operation point to observe this anticrossing. In this way we demonstrate that at optimal angle of incidence the sign of the transverse MO effect can be switched by the geometry of the grating without change of the orientation of the external magnetic field. The observed transverse magneto-optic Kerr effect for near infrared frequencies (around 1 eV) strongly outperforms what can be obtained on uniform ferromagnetic metallic films. Moreover, the sign change of TMOKE without switching the magnetization opens up new possibilities for the design of compact nonreciprocal devices.

[1] G. Armelles, et al., Adv. Opt. Mat., Vol. 1,10-35, (2013) [2] L. Halagačka, et al., J. Magn. Soc. Jpn., 1110140524, (2011)(A) [3] L. Halagačka, et al., Opt. Express, vol. 21, 19, 21741-21755, (2013)

Mueller matrix spectra of the plasmonics grating

P10 TIME-RESOLVED ELLIPSOMETRY STUDIES OF EXCITON-POLARITONS IN A ZnO-BASED PLANAR MICROCAVITY UNDER PULSED EXCITATION Steffen Richter, Chris Sturm, Helena Franke, Rüdiger Schmidt-Grund, Marius Grundmann Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany steffen.richter@physik.uni-leipig.de We present a setup for time-resolved generalized spectroscopic ellipsometry (GSE) using a streak camera as detector with time resolution in the ps range. The setup is also suitable for angular- and time-resolved photoluminescence (PL) and photoreflection (PR) measurements, all also under cryogenic temperatures. For time resolution the signal is modulated by a pulsed laser (FWHM = 1.5 ps). Experimental challenges are in particular GSE alignment and calibration procedures for an exact determination of the phase retardation. Strategies to overcome further experimental difficulties such as phase shifts and beam displacements introduced by the cryostat window will also be presented. The combination of the time-resolved GSE with pulsed photo excitation allows to explore different physical processes: PL probes the occupation, the GSE measurement gives information about the properties of the density of states. Both together allow to deduce the change of the density of states as a function of their occupation. We demonstrate this functionality on exciton-polaritons in a ZnO-based microcavity [1, 2]. These are quasi-particles formed by the strong light-matter coupling between excitons and cavity photons. They inherit exciton spin as well as light polarization, which both are expressed in terms of the pseudospin of an exciton-polariton ensemble. The pseudospin is experimentally accessible through the Stokes vector of the light emitted by the radiative polariton decay. It is subject to a number of effective magnetic fields [3]. A particular kind of effective magnetic field is associated to population imbalances with respect to the different polarization states. Time-resolved GSE under pulsed laser excitation is used to study the (non-linear) effect of the occupation of the lower polariton branch states on their eigenpolarization.

[1] C. Sturm et al.: NJP 13, 033014 (2011) [2] H. Franke et al.: NJP 14, 013037 (2012) [3] I. Shelykh et al.: Semicond. Sci. Technol. 25, 013001(2010)

P11 CHARACTERIZATION OF NANOPARTICLES AT INTERFACES BY IMAGING ELLIPSOMETRY AND BREWSTER ANGLE MICROSCOPY Peter H. Thiesen, Christian Röling Accurion GmbH, Stresemannstr. 30, D-37079 Göttingen, Germany pt@accurion.com The tailored organization of nanoparticles is of increasing technical and scientific interest. Nanoparticles at the air/water interface are used in an increasing number of applications to produce 2D colloidal crystals or nanowires. Gil et al. [1] monitored the formation of 2D colloidal crystals by the Langmuir–Blodgett technique by Brewster angle microscopy. Zang et al. [2] have also studied silica nanoparticle layers spread at the air/water interface. They studied the two types of layers by multiple angle of incidence ellipsometry. For data interpretation, they introduce a two-layer model which enables them to evaluate the radius of interfacial aggregates and their contact angle at the air/water interface. One step further coming from a complete layer are structured aggregations of nanoparticles like line shaped organisation. Different line shaped pattern of SiO2 nanoparticles on a glass substrate were characterised by spectroscopic imaging ellipsometry in the wavelength range between 360 and 1000 nm. The optical model including packing density and surface roughness was in good agreement with AFM measurements. Another approach to organize nanoparticles was reported by Volinsky and Jalinek [3]. They demonstrate the formation of a network of elongated Au “wires”. The laser-induced structured films exhibited high stability and could be transferred from water onto solid substrates without disrupting the Au organization. To follow the formation at the liquid/solid interface, Brewster angle microscopy was used.

[1] Gil, M. Vaupel, F. Guitiana, D. Möbius (2007) Journal of Materials Chemistry 17: 2434–2439. [2] D. Zang, A. Stocco, D. Langevin, B. Weib, B.P. Brinks (2009) Phys. Chem. Chem. Phys. 11:

9522–9529. [3] R. Volinsky, R. Jelinek (2009) Angew. Chem. Int. Ed. 48: 1 – 4.

Ellipsometric contrast micrographs of different line shaped pattern of SiO2 nanoparticles on a glass substrate. The sample shown was provided by the research group of Professor Y. Mori, Doshisha University, Japan.

P12 EVALUATION OF VERTICAL INHOMOGENEITY IN CHEMICALLY ETCHED POROUS SILICON LAYERS WITH VUV-NIR AND FTIR ELLIPSOMETRY E. Agocs1, 2, B. Fodor1, 3, G. Gautier4, F. Cayrel4, Peter Petrik1, 2, P. Basa5, L. Makai5, D. Alquier4, M. Fried1, 4

1 Research Centre for Natural Sciences (MTA TTK MFA), Institute for Technical Physics and Materials Science, H-1121 Budapest, Konkoly Thege u. 29-33, Hungary

2 University of Pannonia, Faculty of Information Technology , Doctoral School of Molecular- and Nanotechnologies, Egyetem u. 10, Veszprem, H-8200, Hungary

3 University of Pécs, Faculty of Science, 7624 Pécs, Ifjúság útja 6, Hungary 4 Université François Rabelais, GREMAN, pôle MTECH, 16, rue Pierre et Marie Curie, B.P.

7155, F37071 Tours Cedex, France 5 Semilab Semiconductor Physics Laboratory Co. Ltd., Prielle K. u. 2., Budapest, Hungary 1117

agocs.emil@ttk.mta.hu Porous silicon layers (PSL) would have important applications in radio frequency devices for local electrical isolation or in power electronics as anisotropic structures. Our work considered the evaluation of several micrometer thick PSL-s with VUV-NIR and FTIR spectroscopic ellipsometry. The PSLs were prepared by electrochemical etching (anodic dissolution) of crystalline silicon wafers in hydrofluoric acid based electrolytes. By varying the electrolyte composition or the anodizing conditions like the applied current or the etching duration, the porous layer thickness, the porosity and the pore dimensions could be set in a controlled way. Several different optical models for ellipsometric evaluations were verified in terms of fit quality, parameter uniqueness and parameter relevance. The thickness and the porosity values were cross-checked with electron microscopy. A first order approach to describe the layer was the use of multiple independent effective medium sublayers of varying ratio of c-Si to void. The number of independent sublayers could not be increased to an arbitrarily high number due to parameter cross-correlations, but even with a model of three independent sublayers, good information about the total thickness of the porous layer and the in-depth distribution of the porosity could be obtained from the evaluations. A graded model, where the in-depth porosity was described with a linear function, was a good improvement over the independent multilayered model. Further improvements could be attained by applying two coupled linear functions. We note, that additionally to the 4 parameters describing the coupled linear functions and the two thickness values, another parameter (with a fixed value during the fitting procedures) would be the number (N) of homogeneous thin sublayers used for the graded models. As N increases, the fit quality significantly improves until around N = 100. This N dependence is emphasized for the thicker layers.

In-depth volume fraction of void described with two coupled linear functions.

P13 DETERMINATION OF OPTICAL PARAMETERS AND ELECTRICAL CONDUCTIVITY OF TRANSPARENT CONDUCTING OXIDES BY SPECTROSCOPIC ELLIPSOMETRY Chaman Singh, Shyama Rath University of Delhi, Department of Physics and Astrophysics chamans6@gmail.com Transparent conductive films of undoped ZnO were prepared on Si substrates by rf-sputtering and subsequently annealing in an oxygen atmosphere. The optical constants (refractive index and absorption co-efficient) as well as carrier concentrations were comprehensively determined from spectroscopic ellipsometry. The figure shows the real and imaginary parts of the dielectric function for both as-deposited and annealed films. The measurements revealed a high transparency in the visible range for both as-deposited and annealed films. In the near infrared region however, the as-deposited films were found to be highly absorbing as compared to the annealed films. The optical band gap exhibits a red shift from 3.6 eV to 3.2 eV after annealing. The absorption of near infrared radiation and the change in the bandgap is discussed in the light of Burstein-Moss theory which arises due to the filling of the conduction band with additional n-type carriers [1]. The carrier concentration calculated from the position of the plasmon frequency in as-deposited films was found to be high (1020/cm3) and matches well with values obtained with the Hall measurements. The results are correlated to the stoichiometry of the films determined from Rutherford backscattering measurements. [1] A. Dixit, C. Sudakar, R. naik, V. M. Naik, and G. Lawes Appl. Phys. Lett. 95, 192105 (2009).

Imaginary and real part of dielectric function of as-deposited and annealed films of ZnO.

P14 MUELLER-MATRIX-ELLIPSOMETRY ON BLAZED GRATINGS PRODUCED BY REACTIVE ION BEAM ETCHING C. Bundesmann1, R. Fechner1, M. Burkhardt2, M. Helgert2, A. Gatto2, F. Frost1

1 Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig 2 Carl Zeiss Jena GmbH, Carl-Zeiss-Promenade 10, 07745 Jena

carsten.bundesmann@iom-leipzig.de We have performed Mueller-matrix spectroscopic ellipsometry (MM-SE) measurements on blazed grating structures. The grating structures are produced by reactive ion beam etching (RIBE) [1]. Here, RIBE allows the proportional transfer of grating structures defined by e.g. interference lithography into the optical substrate material. Depending on the parameters of the etching process, a vertical pattern scaling very much smaller than 1 and up to about 10 is feasible. A set of samples, which document selected process steps, is characterized by atomic force microscopy (AFM) concerning the topography and by MM-SE concerning the optical properties. A full set of MM-spectra are recorded at azimuthal orientations for a full rotation at steps of 18° and at three angles of incidence (65°, 70°, 75°). AFM shows the pattern transfer from the photoresist into the fused silica. Due to the different etch rates of the photoresist and the fused silica; two different slopes can be identified at intermediate process steps. MM-SE data reveal characteristic symmetry relations with respect to azimuthal orientation, which are strongly correlated with the topographic properties. Unfortunately, a thorough analysis of the MM-SE data is only possible with rigorous means. This analysis is still in progress. The authors gratefully acknowledge financial support by the Federal Ministry of Education and Research within the SHAPION project (FKZ: 13N12150).

[1] F. Frost, R. Fechner, J. Lorbeer, M. Teichmann, A. Schindler, R. Steiner, M. Burkhardt, L. Erdmann, T. Gase, T. Glaser, A. Gatto, Proceedings 3. Kolloquium 'Dünne Schichten in der Optik', Leipzig, (2012), Leipzig, 04.-06.09. 2012, 345 - 349.

Temporal evolution of the grating profile during RIBE. The first profile shows the photoresist profile. After approximately 18 min the profile is completely etched into fused silica. Curves are shifted for clarity.

P15 SOLVENT - NON-SOLVENT MIXTURE INDUCED WRINKLING IN THIN POLYMER FILMS Naval Singh, Manish Kulkarni, Priyanka Sachan, Ashutosh Sharma Indian Institute of Technology, Department of Chemical Engineering, DST unit of Nanosciences, Kanpur, U.P.-208016, India ashutos@iitk.ac.in Wrinkling in thin polymer films is observed under solvent-non-solvent mixture. Experimental measurements of wrinkling in polystyrene (PS) (Mw = 280K) films with thickness ranging from 20 nm to 200 nm are conducted by placing 10 µm drop of dimethyl formamide (DMF)-water mixture. Effect of variation of DMF-water composition on wrinkling behaviour of annealed (at 60° C in vacuum for 1 hr) and unannealed PS films is studied. Wrinkles are observed under drop and at the drop edge between 80 to 96% (v/v) DMF in water. Addition of further DMF in water leads to spontaneous dewetting of PS film. Whereas no wrinkling is observed outside the drop when less than 80% DMF is added to water. In case of unannealed films, it is observed that outside the drop edge, the number density of the wrinkle increases with decrease in film thickness for a given composition of DMF, hence the area enclosed by the wrinkles becomes smaller. However, there is decrease in radial wrinkle propagation length away from the drop with decrease in film thickness. Interestingly, no wrinkling was observed under the drop above 94% DMF concentration. The number density of wrinkles is observed higher under the drop and negligible outside the drop for annealed films as compared to unannealed films. This dissimilar behavior can be attributed to lesser residual stresses in annealed films than in unannealed films.

P16 FROM INSULATOR TO CONDUCTOR: INFRARED REFLECTIVITY OF INVERTED FISHNET DESIGNS Stefano De Zuani1, M. Rommel2, H. Kumric1, A. Berrier1, J. Weis2, B. Gompf1, M. Dressel1

1 Universität Stuttgart , Physikalisches Institut and Research Center SCoPE, Pfaffenwaldring 57, 70550 Stuttgart, Germany

2 Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany stefano.de-zuani@pi1.physik.uni-stuttgart.de Metallo-dielectric nanocomposites exhibit remarkable properties at the percolation threshold. A small variation of the filling factor can lead to a discontinuity in the static conductivity from an insulating to a metallic state. Also in the infrared spectral region, the real permittivity diverges. This behavior can in principle be described by percolation theories, assuming a random distribution of the metallic inclusions inside the insulating matrix. But what happens in ordered structures when the random percolation is suppressed? To answer this question, we perform a systematic study on nearly closed, electron beam lithography patterned, 20 nm thick gold squares of size a on SiO2/Si substrates, forming an inverted fishnet pattern only interrupted by small gaps (~10 nm). These films have filling factors close to unity, but exhibit no dc-conductivity. We perform reflectivity and spectroscopy ellipsometry investigations in the range of 400 to 2400 nm, increasing the gold filling factor by changing the size of the squares a from 100 nm to 3600 nm and keeping the separation gap g around 10 nm. In the figure, the SEM image of the gold squares with a diameter ~100 nm and gap of ~10 nm is presented. Our measurements reveal that even square arrays with a filling factor of 0.9 exhibit a strongly decreasing reflectivity in the near infrared frequency range. Modelling the optical response of the films with an effective medium approximation is not straight forward. Indeed, the effective parameters depend not only on the incidence angle, what is expected for an ordered plasmonic structure, but also on the specific substrate. On the other hand, solving Maxwell’s equations under the full 3D boundary conditions using the commercial program CST leads to reasonable agreement between theory and experiment. Regions of very large field enhancement in the gaps can be seen over a large frequency range and are responsible of the trapping of the incident light in the patterned structure.

SEM image of a fabricated square array with size a ~100 nm and gap g ~10 nm.

P17 METALLIC NANOPARTICLES UNDER MILD HEATING – REAL-TIME MONITORING BY SPECTROSCOPIC ELLIPSOMETRY Jaroslav Kousal, Ondřej Kylián, Jan Hanuš, Juraj Čechvala, Tereza Steinhartová, Jan Prokeš, Hynek Biederman Charles University in Prague, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V Holešovičkách 2, 18000 Prague, Czech Rep. jaroslav.kousal@mff.cuni.cz Metallic nanoparticles are known to have properties significantly different from the bulk material. At the size range of units of nanometers this is true also for their electrical conductivity and the melting point. While the melting point of most metals is above 1000° C, the melting point of nanoparticles can be by several hundred degrees lower. We used a single-stage gas aggregation source based on the planar magnetron [1] to produce various kinds of nanoparticles. In this study, we focused on the Pt, Au and Cu nanoparticles. Thin films of these nanoparticles were deposited on the substrate and their optical properties were monitored using spectroscopic ellipsometry during subsequent heating. Already below 200° C a significant changes were observed. This can be attributed to the changes of morphology due to partial melting of particles and also to the subsequent changes in free-carrier conductivity. Additionally, changes of the electrical conductivity of the films of nanoparticles were directly measured.

[1] Polonskyi, O; Solar, P; Kylian, O; Drabik, M; Artemenko, A; Kousal, J; Hanus, J; Pesicka, J; Matolinova, I; Kolibalova, E; Slavinska, D; Biederman, H, Nanocomposite metal/plasma polymer films prepared by means of gas aggregation cluster source, THIN SOLID FILMS, vol. 520, is. 12, p.4155-4162, 2010

P18 MUELLER MATRIX ELLIPSOMETRIC INVESTIGATIONS ON STRONGLY SCATTERING GRANULAR FILMS Katharina Junge, Bruno Gompf, Audrey Berrier, Martin Dressel Universität Stuttgart, Physikalisches Institut, Stuttgart, Germany b.gompf@physik.uni-stuttgart.de Ellipsometric measurements are usually described in the framework of Fresnel’s equations, whereas the scattering of light on spherical particles is described by Mie-theory. But what happens when strongly scattering dielectric Mie-particles form a thin film? For our eyes transparent samples with dielectric inclusions appear white. On the one hand one expect diffuse reflection close to that of a Lambertian surface, on the other hand new phenomena can arise, like the appearance of a coherent backscattering peak or Anderson localization, i.e. the complete trapping of light in the medium. Even though we are surrounded by white surfaces in daily life, up to now only few systematic Mueller matrix (MM) investigations on strongly scattering samples have been published. We present a systematic investigation of granular ZnO films of different thickness composed of nanoparticles with 300 nm diameter on glass. On these samples we perform MM ellipsometry as well as MM scatterometry over a broad angular range (20° to 90°) at different wavelengths ranging from the blue up to the near infrared. Although the samples are extremely rough, they exhibit a strong reflection peak additionally to the broad incoherent background due to subsurface scattering. The peak intensity depends on the wavelength and on the incident polarization with a Brewster-angle corresponding to the effective n of the granular film. In principle non-depolarizing samples can be described by 7 independent optical parameters and homogenous depolarizing samples by 10. In contrast white samples are inherently inhomogeneous. Therefore a careful analysis of the measured MMs is necessary. To reveal the physics behind the different scattering phenomena we analyze the measured MMs by polar decomposition. We found that the degree of polarization in reflection strongly depends on wavelength and that the depolarization of the off-specular incoherent background cannot simply be described by a perfect depolarizer.

Scattered light intensity of a 18 µm thick granular ZnO film. Angle of incidence 20°, wavelength 660 nm.

P19 IMPACT OF WATER DROPLETS ON A SUPERHYDROPHOBIC, NANOSTRUCTURED SURFACE IN THE PRESENCE OF AN EXTERNAL ELECTRIC FIELD Georg M. Widholz1, Erik Förster1, Wolfgang Mönch2, Wenwen Chen3, Jan-Henning Dirks3, Joachim Spatz3, Robert Brunner1

1 University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany 2 OSRAM Opto Semiconductors GmbH, Leibnizstr. 4, 93055 Regensburg, Germany 3 Max Planck Institute for Intelligent Systems, New Materials and Biosystems, Heisenbergstr. 3,

70569 Stuttgart, Germany robert.brunner@fh-jena.de The possibility to control the dynamic interaction of fluids with micro- and nano-structures has a strong relevance for the development of surface characteristics such as self-cleaning or anti-fogging properties. Significant key-factors influencing the interaction behavior of the fluid with the surface are the topographical dimensions and shape of the micro- and nanostructures and the chemical composition of the contact layer. Further control possibilities are using electrowetting effects in which an applied external electrical field modifies the surface tension between fluid and the boundary surface and deforms or moves the liquid droplets. A recent application field of electrowetting concerns switchable liquid lenses. In this contribution we present the experimental results of drop impingement on various nano-structured, superhydrophilic and superhydrophobic surfaces in the presence of an external electric field. As basic samples we used artificial ‘moth-eye structures’, prepared in a layer of SiO2 covering a metallic substrate. The manufacturing process of these quasi-periodic subwavelength structures relies on a combination of block copolymer micelle nanolithography (BCML) followed by a reactive-ion-etching (RIE) process. Super-hydrophilicity and super-hydrophobicity is controlled by specific surface treatment, e.g. by coating with FDTS (perfluorodecyltrichlorosilane). The dynamic interaction of the droplets with the surface was recorded by a high speed camera system. For the different experiments the droplet volume, the impingement velocity and the strength of the applied external electrical field was varied. From the measured results, the oscillating contact angles, the contact lengths and the droplet heights, were evaluated. In an electric field >1 kV/mm the impinging droplet shows a strong repellent behavior after surface contact, an effect which may be applied for surfaces cleaning processes.

A 80 µl water droplet impinging on a nanostructured, FDTS coated, superhydrophobic surface. Additionally, an external electrical field (0.5 kV/mm) was applied. After the contact with the surface, the droplet shows a strong repellent behavior

P20 COMBINATION OF SCALAR DIFFRACTION THEORY AND RAYLEIGH-RICE THEORY IN SPECTROSCOPIC ELLIPSOMETRY OF RANDOMLY ROUGH SURFACES: APPLICATION TO BOUNDARIES OF EPITAXIAL ZnTe FILMS Ivan Ohlídal1, David Nečas1, 2, Daniel Franta1, 2

1 Masaryk University, Faculty of Science, Department of Physical Electronics, Kotlářská 2, 611 37 Brno, Czech Republic

2 Masaryk University, CEITEC - Central European Institute of Technology, Kamenice 5, 625 00 Brno, Czech Republic

ohlidal@physics.muni.cz Randomly rough surfaces encountered in various fields of basic and applied researches often exhibit roughness composed of one component with small spatial frequencies and second component with large spatial frequencies. This is also true for randomly rough surfaces exhibiting wide intervals of spatial frequencies. Optical quantities such as reflectance and ellipsometric parameters of these surfaces can not be expressed using a single theory such as the scalar diffraction theory (SDT) and Rayleigh-Rice theory (RRT). Therefore, a combination of two or more theories must be employed for expressing the optical quantities of the surfaces mentioned above. Here an approximative combination of SDT and RRT with taking into account slopes and shadowing on the surfaces will be used to express the reflectance and associated ellipsometric parameters of these surfaces covered with very thin layers. It will be shown that the formulae derived within this approach extend our possibilities of characterization of these surfaces covered with very thin films using reflectometry and variable angle spectroscopic ellipsometry. The suitability of the approach will be illustrated using characterization of the rough upper boundaries of ZnTe films deposited by molecular beam epitaxy onto GaAs single crystal substrates. The optical quantities were measured within spectral range 200 - 480 nm where the ZnTe films were not transparent. Thus, the measured reflectance and associated ellipsometric parameters corresponded to upper boundaries of ZnTe films covered with very thin layers.

P21 OPTICAL AND MICROSTRUCTURAL PROPERTIES OF THE Au GRANULAR LAYERS Łukas Skowroński, A. Stachowicz, M. K. Naparty, A. A. Wronkowska University of Technology and Life Sciences, Institute of Mathematics and Physics, Kaliskiego 7, 85-789 Bydgoszcz, Poland lukasz.skowronski@utp.edu.pl Gold is widely used in various branches of research and technology (electronics, photonics, biotechnology, etc.) [1, 2]. The Au granular layers (mass thickness ranges from 1 nm to 5 nm) were deposited on Bk7 glass plates (1mm x 25mm x 25 mm) by a thermal evaporation at a pressure of 10-5 Pa. The metal films were grown with a rate 0.01 nm/s. To determine the effective complex dielectric function of the produced layers, <ε(E)> = <ε1(E)> + i<ε2(E)>, the spectroscopic ellipsometry (SE) was applied. These measurements were carried out in a photon energy range from 0.6 eV to 6.0 eV for five angles of incidence (55°≤φ≤75°). Additionally, the surface topography of gold films was investigated using atomic force microscopy (AFM). We parameterized the effective dielectric function of Au layers as a sum of Gaussian and Lorentzian oscillators. The obtained optical spectra demonstrate two types of absorption bands. The strong resonances for the photon energies below 2.5 eV we ascribe to the plasmon oscillators created in the particulate Au films. The absorption features observed for E >2.5 eV are related to the interband transitions in Au.

[1] C.G. Granqvist, Sol. Energy Mater. Sol. Cells 91 (2007) 1529. [2] V. Cantale, F.C. Simeone, R. Gambari and M.A. Rampi, Sens. Actuators, B, 152 (2011) 206.

(a) Imaginary part <e2> of the effective dielectric function of Au layers deposited on Bk7 glass substrate. (b) AFM image of the surface of the Au(5 nm)/Bk7 sample.

P22 RIGOROUS SIMULATIONS AND ANALYSIS OF THE OPTICAL RESPONSE OF SILICA SCULPTURED THIN FILMS Lennart Fricke1, Christoph Grüner2, Carsten Bundesmann2, Rüdiger Schmidt-Grund1, Marius Grundmann1

1 Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany 2 Leibniz-Institut für Oberflächenmodifizierung e.V, Permoserstr. 15, 04318 Leipzig, Germany

lennart.fricke@uni-leipzig.de We present full Mueller matrix spectra of columnar silica sculptured thin films prepared by electron beam glancing angle deposition on silicon substrates in a wide spectral range from 0.5 eV to 6.5 eV. We analyse the data in two ways: (i) using anisotropic effective medium theory and (ii) using simulations based on the Rigorous Coupled Wave Approach. The analysis by means of anisotropic Bruggeman effective medium approximation reproduces the measured data only qualitatively. Especially in the UV spectral range, where the long wavelength assumption of the Bruggeman EMA does no longer hold, the deviation drastically increases. As an alternative we employ the two-dimensional Fourier-Modal-Method, also known as Rigorous Coupled Wave Approach. Here the geometrical model of the samples is taken from scanning electron microscopy images. The dielectric function of the columnar material (silica) is initially chosen to be that of a homogeneous thin film, which can be modelled using the simple Cauchy function. The parameters of the geometry, namely the inter-columnar distance, the radius and the inclination angle of the columns as well as parameters dielectric function are then further optimised using non-linear regression. A comparison of both methods highlights their different limitations for the analysis of complex structures.

P23 A SIMPLE FOURIER-MODAL-METHOD SOLUTION FOR THIN FILMS WITH SLANTED STRUCTURES Lennart Fricke, Rüdiger Schmidt-Grund, Marius Grundmann Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany lennart.fricke@uni-leipzig.de We present a simplified solution for modelling the optical response of slanted 2D periodic diffractive structures used as optical functional coatings in terms of the Fourier-Modal-Method, also known as Rigorous Coupled Wave Approach, which is suited for fast data analysis in real-time ellipsometry. Usually the structure is divided in small homogenous slices and the optical response is calculated with scattering-matrix algorithms. We incorporate the inclination of the structure directly into the first order differential equation for the propagation along the normal direction. This is possible as the in-plane photonic band structure of a two-dimensional slice of the slanted structure is the same for different slices apart from phase-factors. These phase-factors can be expressed by a unitary transformation of the dielectric Toeplitz-matrix. The transformed equation is solved as a matrix eigenvalue problem similar to the in-plane equations. We compare the speed and accuracy of the conventional method with that of our method for different test structures.

Illustration of the two different solution methods. Left: Division of structure in layers. Right: Direct incorporation of the inclination in the propagation (depicted in red)

P24 ADAPTING A COMMERCIAL MICROSCOPE FOR STUDYING NANO-TEXTURED SURFACES Morten Hannibal Madsen and Poul-Erik Hansen DFM A/S, Danish National Metrology Institute, Matematiktorvet 307, 2800 Kgs. Lyngby, Denmark mhm@dfm.dk The developments of production technologies for nano-textured functional surfaces are currently evolving much faster than measurement methods to characterization of the surfaces. The lack of fast and robust characterization methods suitable for implementation in a production environment is a major limiter for the industrial uptake of the technology. By adapting a commercial microscope to detect scattered light, one can get fast and robust optical measurements with resolution in the nanometer range. The adapted microscope targets the central problem of ever decreasing feature sizes and small areas of interest, and the major advantages for using a commercial microscope as a scatterometer are: • Small spot size possible (<100 µm) • Easy to find area of interest • Compact A small area of interest raises two major challenges, to focus the beam and directing the beam at the area. With easy change of objective one can focus the beam to a very small area, and with the possibility to use the instrument as a normal light microscope, finding specific areas are made much easier. Analyses of the recorded spectra are solved using an inverse modeling approach. Both rigorous coupled-wave analysis (RCWA) and finite element method (FEM) computer simulations are used for generating a library of nano-textured surfaces. The simulations require a priori information of the sample, but once generated, it is a very fast method for characterization. The microscope’s measuring capability is compared to a metrology atomic force microscope using both high quality calibration grids and lower quality injection molded plastic samples. It is furthermore demonstrated how such an optical setup can be used outside a research environment, for instance at a production facility.

Reflectance simulation for a single wavelength computed using RCWA.

P25 DETERMINATION OF THE PLASMONIC RESONANCE OF GOLD DOT MICROARRAYS BY IMAGING ELLIPSOMETRY Ovidiu D. Gordan1, Alexander G. Milekhin2, 3, Ekaterina E. Rodyakina2, 3, Christian Röling4, 5, Alexander V. Latyshev2, 3, Dietrich R. T. Zahn1

1 Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz 2 A.V. Rzhanov Institute of Semiconductor Physics, Lavrentiev av. 13, 630090, Novosibirsk,

Russia 3 Novosibirsk State University, Pirogov str. 2, 630090, Novosibirsk, Russia 4 Accurion GmbH, Stresemannstr. 30, 37079 Göttingen, Germany 5 Georg-August-University Göttingen, Institute for Physical Chemistry, Tammannstraße 6, D-

37077 Göttingen, Germany ovidiu.gordan@physik.tu-chemnitz.de One way to strongly increase Raman scattering signals is to use the plasmonic enhancement given by metallic nanostructures. By carefully tuning the dimensionality and periodicity of the nano-clusters to the resonance of the laser lines and to the absorption of the material under investigation, the Raman fingerprint of single molecules or several semiconductor quantum dots can be recorded using the so called Surface Enhanced Raman Scattering (SERS) configuration. In order to optimize the preparation conditions of the SERS substrates, it is crucial to determine the region of the plasmonic resonance. Here we will look at periodic gold (Au) nano-cluster arrays fabricated on silicon (Si) by direct electron beam writing. While electron beam writing is a relatively slow and expensive technique for producing large SERS substrates, it is very versatile in fabricating small arrays (µm square areas) with different nano-cluster sizes and periodicities on the same chip. Challenging remains the determination of the plasmonic resonances, as conventional ellipsometry setups lack the necessary lateral resolution. Therefore the structures were investigated using an imaging micro-ellipsometer from Accurion (EP3-SE). The measurements performed in a spectral range from 365 to 1000 nm were modelled using a Maxwell-Garnett Effective Medium Approximation (MG-EMA) consisting of Au and a void fraction. As shown in the figure, it is remarkable that the dielectric function obtained for the MG-EMA layer is almost identical to the effective dielectric response of the regions of interest. Even if the Au clusters have diameters below the period length, it is obvious that the optical response of the system is dominated by the optical properties of the metallic structures. In this case the spectral region of the plasmonic resonance can be unambiguous determined by direct inspection of the effective measured optical response with lateral resolution down to 1 µm.

Left – delta contrast image under a 20x objective of 10 x 10 µm areas of gold clusters with a period of 150 nm and diameters from 109 nm to 133 nm. The regions of interest (ROI) from where the experimental points are evaluated are marked in the figure. Right – comparison of the modelled extinction coefficient k and the measured effective extinction coefficient <k>.

P26 MUELLER MATRIX DECOMPOSITION OF DEPOLARIZING METALLIC SAMPLES Maria de Lourdes Miranda-Medina1, 2 and K. Hingerl2 1 AC²T research GmbH - Austrian Center of Competence for Tribology, Viktor-Kaplan-Str. 2, Wiener

Neustadt, 2700, Austria 2 Johannes Kepler University, Altenberger Str. 69, Linz, 4040, Austria medina@ac2t.at Scattered light from rough surfaces has been analyzed through various optical methods. In particular, in the most of the ellipsometric models the roughness is represented by a layer characterized by means of effective medium approximation (EMA). Nevertheless, when the roughness of the samples is higher than few nanometers one can alternatively evaluate the quality of the surface by studying how it depolarizes the reflected light. This information can be extracted as Lu and Chipman proposed [1], by decomposing the measured Mueller matrix in three matrices associated to a retarder, a diattenuator and a depolarizer. In this work we present the Mueller matrix decomposition of a set of polished metallic samples with different initial roughness, previously evaluated by using a confocal-interferometrical microscope. Based on this analysis the degree of depolarization that is extracted from the measured Mueller matrix can be related to the roughness of the samples.

[1] Shih-Yau Lu and Russell Chipman, J. Opt. Soc. Am. A/Vol. 13, No. 5/May 1996.

P27 IMPROVE THE PERFORMANCE OF FOCUSED BEAM ELLIPSOMETER BY USING INTER-LAYER CROSSTALK MODELING Attila Sütő and Zoltán Kárpáti Semilab Zrt. H-1117 Prielle Kornélia str. 2. Budapest, Hungary attila.suto@semilab.hu It is very important to measure layer structures within a well-defined area so called on patterns. In many cases the pattern size achieved the size of focused beam considered unique applications. So-called beam overlapping causes perturbation in spectra because the focused beam is reflected from the pattern and the undesirable area simultaneously. Our goal to take into account the inter-layer crosstalk instead of modifying the imaging system being flexible fitting to different applications. By using a well optimized focused spectroscopic ellipsometer with 50 µm spotsize, we have done experiments to measure smaller patterns as spotsize of optical system taking into account the intel-layer crosstalk. Theoretical approach based on inhomogeneous sample the overall (psi, delta) spectra is the mixture of the (pis, delta) of the separate layers. To calculate the overall spectra the Stokes vectors of the adjacent layers need to be calculated. The overall Stokes vector of inhomogeneous layer is a weighted of the Stokes vectors reflected from layer 1 and layer 2 respectively. Having calculated the overall Stokes vector the overall (psi, delta) can be calculated in function of stokes parameters and overlapping parameter. The calculation was applied for special patterns where the inter-layer crosstalk has strong effect (3 nm SiO2 on Si with aluminum layer around it). After comparing the evaluated spectra before taking into account inter-layer cross talk and after applying the inter-layer model we can conclude that the new approach improve the performance if the pattern is smaller than spotsize. Applying the method for silicon oxides and aluminium as harmful layer we could eliminate the inter-layer crosstalk up to 10% overlapping. System could measure smaller patterns dues to new method at the same spotsize.

Inter-layer crosstalk

P28 ELLIPSOMETRY STUDY OF THE LOCAL SURFACE PLASMONIC RESONANCE IN SILVER NANOSTRUCTURES AS A FUNCTION OF TEMPERATURE S. Nikipar, Stefan Moras, O. Gordan, D. R. T. Zahn Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz moras@hrz.tu-chemnitz.de Nowadays nanosized metal particles attract a lot of interest, due to their extraordinary optical properties. When these nanoparticles are excited by light, they exhibit localized surface plasmon resonance (LSPR). The advancements in nano fabrication of the last decade have enabled the use of LSPRs for light manipulation at the nanoscale and makes them valuable for many applications ranging from biosensing to surface Raman spectroscopy. Optical properties associated with LSPRs are determined by shape, size, structure, and local dielectric environment. It is necessary to modify and tune the optical properties of these nanoparticles in order to exploit their full potential by controlling all parameters that determine the LSPR characteristics. Therefore, fundamental studies of tunable optical properties of LSPR metal nanoparticles are of particular interest. In the present work we investigated the effect of annealing on nanoparticles which strongly alters the LSPR and provides an easy method to tune the LSPR. We applied the annealing process on different sizes of silver triangular nanostructures on silicon and glass substrates produced by nanosphere lithography method. The measurements were performed by spectroscopic ellipsometry for the 70° angle of incidence and energy range from 0.7 eV to 5 eV which allows us to assess and monitor the temperature effect on the optical properties of metallic nanostructures. The figure shows the real part of the effective dielectric function of the silver nano triangle structures on silicon substrate. A significant change can be seen around 180° C to 300° C and no noticeable change is visible after 300° C.

Real part of the effective dielectric function of the silver nano triangle structures on silicon substrate as a function of energy at room temperature (RT), different heating temperatures and at room temperature after cooling (RT, AC) of 500° C.

P29 OPTICAL FEATURES OF FeTe(1-x)Se(x) SUPERCONDUCTORS PROBED BY SPECTROSCOPIC ELLIPSOMETRY Krzysztof Dorywalski1, Dariusz J. Gawryluk2, Rüdiger Schmidt-Grund3, Lennart Fricke3, Marius Grundmann3, Marek Berkowski2, Michał Piasecki4

1 Koszalin University of Technology, Poland 2 Polish Academy of Science, Institute of Physics, Warsaw, Poland 3 University of Leipzig, Germany 4 J. Dlugosz University, Częstochowa, Poland

krzysztof.dorywalski@tu.koszalin.pl We present results of ellipsometric measurements of FeTe(0.5)Se(0.5) and FeTe(0.65)Se(0.35) crystals in the spectral range 0.5–8.5 eV and 0.05–0.55 eV (530–4000 cm-1). Ellipsometric spectra were measured at different fixed temperatures comprising regions below and above magnetic as well as superconducting transition (10–300 K). The complex dielectric functions were evaluated by optical model taking into account surface inhomogeneities. The results are compared with theoretical studies of electronic structure calculations. Starting with the discovery of superconductivity in LaFeAsO(1-x)F(x) in 2008 [1], iron-based pnictides and chalcogenides attract much attention as a new class of high-temperature superconductors with an evidence of non-BCS theory of superconductivity. Among them, the systems from '11' group, namely Fe(1+x)Se, Fe(1+x)Se(1-y)Se(y) and Fe(1+x)Se(1-y)S(y), have the simples crystallographic structure with iron atoms arranged in characteristic planes [2]. Although much effort has been made to understand these new superconductors, the electron pairing mechanisms as well as coexistence with magnetism are still far from explicit explanation. The optical experiments along with the theoretical electronic structure calculations as well as the result of recent studies on pressure-induced enhancement of the superconducting properties [3] can add more information on this subject.

[1] Y. Kamihara, T. Watanabe, M. Hirano, H. Hosono, J. Am. Chem. Soc. 130(2008) 3296 [2] K. Deguchi, Y. Takano, Y. Mizuguchi, Sci. Technol. Adv. Mater. 13 (2012) 054303 [3] J. Pietosa, D. J. Gawryluk, R. Puzniak, A. Wisniewski, J. Fink-Finowicki, M. Kozlowski, M.

Berkowski, J. Phys.: Condens. Matter 24 (2012) 265701

P30 OPTICAL PROBE OF FERROELECTRIC ORDER IN BULK AND THIN-FILM PEROVSKITE TITANATES Matthias Rössle1, 2, C. N. Wang2, P. Marsik2, M. Yaydi-Rizi2, K. W. Kim2, 3, A. Dubroka2, 4, I. Marozau2, C. W. Schneider5, J. Humlicek4, D. Baeriswyl2, C. Bernhard2

1 University of Potsdam, Institute of Physics and Astronomy, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam, Germany

2 University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Musée 3, CH-1700 Fribourg, Switzerland

3 Chungbuk National University, Department of PhysicsCheongju 361-763, Korea 4 Masaryk University, CEITEC - Central European Institute of Technology, Department of

Condensed Matter Physics, Kotlarska 2, CZ-61137 Brno, Czech Republic 5 Paul Scherrer Institut, CH-5232 Villigen, Switzerland

matthias.roessle@uni-potsdam.de We have measured the temperature dependence of the direct band gap Eg in SrTiO3 and BaTiO3 and related materials with quantum-paraelectric and ferroelectric properties using spectroscopic ellipsometry. We relate the anomalous temperature dependence of Eg to the pronounced changes of the dielectric function in the vicinity of the ferroelectric transition that can be accounted for in terms of the Fröhlich electron-phonon interaction with an optical phonon mode, the so-called ferroelectric soft mode. In addition, we demonstrate that these characteristic changes of Eg can be readily detected even in very thin films of SrTiO3 where a strain-induced ferroelectric order has been recently observed. We show that optical spectroscopy thus can be used as a sensitive probe of ferroelectric order in very thin films of these titanates and suggest that this result will allow the detection of ferroelectric order in similar thin film samples, multilayer structures, and buried layers or even interfaces in devices without using electrical contacts.

P31 OPTICAL PROPERTIES OF GADOLINIUM-IRON GARNET BY SPECTROSCOPIC ELLIPSOMETRY Mangesh S. Diware1, Junho Choi1, Han Gyeol Park1, Yuri Kang1, Young Dong Kim1, Chang Bae Park2, Kwangwoo Shin2, Kee Hoon Kim2

1 Kyung Hee University, Nano-Optical Property Laboratory and Department of Physics, Seoul 130-701, Republic of Korea

2 Seoul National University, CeNSCMR, Department of Physics and Astronomy, Seoul 151-747, Republic of Korea

ydkim@khu.ac.kr Ferrite-based rare earth garnets are very interesting materials which possess unique optical, magnetic, and mechanical properties. They are also chemically stable, which makes them promising candidate for applications like electrochemical devices, integrated circuits, and optical devices. To understand the underlying physics, to design more efficient application, and to provide experimental basis for a band calculations, accurate dielectric function – accurate critical point (CP) energies are needed. Dielectric function (ε) of garnet-type Gd3Fe5O12 single crystal is reported. The measurement was performed by homemade rotating compensator spectroscopic ellipsometer in the energy range 1.5 to 6 eV. In-situ wet-chemical etching was applied to minimize surface overlayers and the whole measurement was done in a nitrogen atmosphere to reduce further contamination. The CP energies were obtained from numerically calculated second energy derivative of the measured data. This study could be helpful in designing better multilayer structures for high performance oxide electronics and also in understanding interface physics of these multilayers.

Real (ε1) and imaginary (ε2) part of the pseudo-dielectric function (ε = ε1 + iε2) of Gd3Fe5O12 single crystal.

P32 INVESTIGATION OF DIAMOND-LIKE CARBON STRUCTURE USING A COMBINATION OF SYNCHROTRON AND CONVENTIONAL ELLIPSOMETRY AND SPECTROPHOTOMETRY David Nečas1, 2, Daniel Franta1, 2, Pavel Ondračka1, Lenka Zajíčková1, 2, Mihai George Mureşan1, Vratislav Peřina3, Romana Mikšov 3

1 Masaryk University, CEITEC - Central European Institute of Technology, RG Plasma Technologies, Kotlářská 2, Brno, Czech Republic

2 Masaryk University, Faculty of Science, Department of Physical Electronics, Kotlářská 2, Brno, Czech Republic

3 Academy of Science of the Czech Republic, Nuclear Physics Institute, Hlavní 130, Řež, Czech Republic

yeti@physics.muni.cz A series of diamond-like carbon (DLC) films with varying hydrogen concentration was prepared from methane using PECVD (plasma-enhanced chemical vapour deposition) and the hydrogen concentration was measured using a combination of ERDA + RBS. The dielectric response of the films was investigated in an ultra-wide spectral range from 0.009 to 50 eV using a combination of synchrotron ellipsometry at BESSY II, synchtrotron reflectometry at Elettra, and conventional ellipsometry and spectrophotometry. The data sets from all instruments were fitted together using a single consistent dispersion and structural model. The dispersion model was based on the utilisation of the Thomas–Reiche–Kuhn (TRK) sum rule and covered all types of transitions, from phonon absorption to σ → σ* and π → π* valence-to-conduction electron excitations to high-energy excitations to core electron excitation.

Overview of all experimental data and their coverage of the entire spectral range for a selected sample (CH30).

P33 INFRARED ELLIPSOMETRY STUDY OF THE FREE CHARGE CARRIERS AT THE LAO/STO (110) AND (111) INTERFACES Meghdad Yazdi-Rizi1, M. Rössle1, C. N. Wang1, P. Marsik1, C. Bernhard1, G. Herranz2

1 University of Fribourg, Department of Physics and Fribourg Center for Nanomaterials, Chemin du Muse´e 3, CH-1700 Fribourg, Switzerland

2 Campus de la UAB, Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Bellaterra 08193, Catalonia, Spain

meghdad.yazdi@unifr.ch The discovery of highly mobile charge carriers at the interface between the two insulators LaAlO3 and SrTiO3 with the orientation of the STO substrate along the [001] directions has raised great interest in their origin. The most popular explanation is in terms of a divergence of the electrostatic potential which arises from a polar discontinuity at the interface and a subsequent electronic redistribution across the LaAlO3 layer. In this context it is very interesting that the conducting interface has recently also been observed in heterostructures which are grown on STO substrates with other crystallographic orientations like [110] and [111] and thus a different stacking of polar layers. We investigate the electronic properties of the interfacial charge carriers in these samples using far- and mid-infrared ellipsometry. In particular, the analysis of the so-called Berreman-mode allows us to determine the concentration and mobility of the confined charge carriers with an optical technique.

P34 EFFECT OF A Ge UNDERLAYER ON THE MIR-VIS-UV OPTICAL RESPONSE OF Ag THIN FILMS Aleksandra A. Wronkowska1, A. Wronkowski1, M. Trzcinski1, P. Wróbel2, T. Stefaniuk2, T. Szoplik2

1 University of Technology and Life Sciences, Institute of Mathematics and Physics, Kaliskiego 7, 85-789 Bydgoszcz, Poland

2 University of Warsaw, Faculty of Physics, Pasteura 7, 02-093 Warsaw, Poland aleksandra.wronkowska@utp.edu.pl A beneficial effect of incorporating a wetting layer on surface smoothness and percolation threshold in Ag films grown on the dielectric substrates [1] can be a prerequisite for creation of the long-range surface plasmon polaritons. Here, we present the optical properties of the 100 nm-thick Ag layers fabricated on the epi-polished silica and sapphire plates using e-beam physical vapour deposition at two temperatures: 180 and 295 K (RT). Silver films were grown with rate of 1 nm/s directly on the substrates as well as on the substrates covered by an ultra-thin layer of evaporated germanium. Deposition rate of Ge was 0.05 nm/s. A 1 nm-thick Ge undercoating layer considerably decreases roughness of Ag-film surface. The combination of ex situ spectroscopic ellipsometry and reflectance measurements in air have been used for determining the optical constants of the produced Ag samples in the spectral range from 0.2 to 6.5 eV. The influence of surface roughness on the experimental spectra is corrected by introduction of intermediate layer at the Ag/air interface in data modelling. The microstructural changes, which arise during film growth and post-deposition ageing in Ar at room temperature, efficiently alter the optical spectra of RT samples with Ge nucleation layer with respect to optical behaviour of other Ag samples. A relatively strong peak positioned at about 2 eV appears in the imaginary parts of their dielectric functions. This additional absorption band can be reproduced by a Lorentzian-type oscillator, which increases, broadens and shifts towards longer wavelengths with increasing time of ageing. The Ge diffusion through the Ag films and its segregation to the surface, evidenced by the XPS and compositional depth profile measurements, is most probably responsible for the observed effects in optical spectra and contribute to increase of dc-resistivity of Ag/Ge/SiO2(Al2O3) samples produced at 295 K.

[1] V. J. Logeeswaran et al., Nano Letters 9 (2009) 178-182.

Representative imaginary parts of the dielectric functions for as-prepared and aged Ag thin films deposited on Ge wetting layer. Dashed curves refer to the pseudo-optical constants.

P35 PERCOLATION BEHAVIOR OF VANADIUM DIOXIDE THIN FILM DURING PHASE TRANSITION Jean-Christophe Orlianges1, R. Zaabi1, C. Champeauc1, A. Crunteanu2

1 CNRS, University of Limoges, SPCTS UMR 7513, 12 rue Atlantis, 87068 Limoges, France 2 CNRS, University of Limoges, XLIM Research Institute UMR 7252, 123 avenue Albert

Thomas, 87060 Limoges, France jean-christophe.orlianges@unilim.fr Among vanadate family performing metal to insulator transitions (MIT) [1], vanadium dioxide (VO2) is the most intensively studied for the past several decades. Indeed, vanadium dioxide undergoes an abrupt reversible first order phase transition within temperature from semiconductor monoclinic phase (M1, M2) to metallic rutile (R) phase. The remarkable character of this transition is what takes place at a temperature close to room temperature, at about 68° C. MIT can be achieved with other external stimuli than temperature such as light [2], electric field [3], mechanical strain [4]. MIT mechanism in VO2 has been a topic of debate between two fundamental descriptions: a Mott transition driven by electron-electron correlation and a Peierels transition driven by electron-lattice interactions. A Jobin Yvon–UVISEL spectroscopic ellipsometer (SE) with a temperature cell has been used to characterize the optical properties of vanadium dioxide thin films. The SE measurements are performed at two different incidence angles 60° and 70° from room temperature to 95° C. The optical constants of VO2 thin films as a function of the frequency were determined by a classical dispersion model based on the sum of Lorentz and Drude oscillators. Spectroscopic ellipsometry spectra at set temperatures are fitted with an effective medium approximation (EMA) model to describe the dielectric constant of mixed phase material: pure semiconductor VO2 obtained at low temperature (20° C) and pure metallic VO2 (95° C). The figure displays the fraction of metallic phase (resp. semiconductor phase) as function of temperature. Then, electrical resistivity as function of composition was derived from this effective medium compositional analysis and we observe and study the percolation behaviour.

[1] F. Morin, Phys. Rev. Lett. 3, 34 (1959) [2] A. Cavalleri et al., Phys. Rev. Lett. 87 237401 (2001) [3] G. Stefanovich et al., J. Phys. Condens. Matter 12 8837 (2000) [4] J. Cao et al., Nat. Nanotechnol. 4, 732 (2009)

Volume fractions of metallic phase (resp. semiconductor phase) during VO2 MIT for heating and cooling processes

P36 APPROACHES TO CALCULATE DIELECTRIC FUNCTION OF VERY THIN CARBON LAYERS FROM SPECTROSCOPIC ELLIPSOMETRIC MEASUREMENTS Zsuzsanna Pápa, Judit Budai, János Csontos, Zsolt Toth University of Szeged, Department of Optics and Quantum Electronics, H-6722 Szeged, Dom ter 9., Hungary zpapa@titan.physx.u-szeged.hu In this work, ellipsometric study of very thin carbon layers is presented. Our aim was to compare the dielectric and structural properties of thin carbon layers and graphene. Thin carbon layers were produced by pulsed laser deposition (PLD) onto different substrates: silicon with native oxide layer, silicon with a thick, thermalized oxide layer and silicon threated by hydrofluoric acid. Since PLD provides a linear connection between pulse number and layer thickness, it allows scaling down the layer thickness up to single or a few atomic layer coverage of the substrate surface. Parameters of the PLD (pulse number, substrate temperature and average fluence) have been varied in order to study the crystallinity change i.e. formations of amorphous, diamond-like or graphite-like and graphitic structures. Samples were investigated with ellipsometry, Raman-spectroscopy and atomic force microscopy. Emphasis is placed on the ellipsometric results, because the evaluation of such thin films is a challenging problem of its own. Ellipsometric measurements were done after each step of the process (thermal oxidation, etching, heating, deposition), to get the most information about the samples. Several evaluation procedures have been performed (e.g. multisample method, point-by-point analysis) and discussed strictly from the point of view of applicability. Our results will be compared with the optical constants of graphene.

P37 ELLIPSOMETRIC INVESTIGATION OF Cd(1-x)Hg(x)Te ALLOY COLLOIDAL QUANTUM DOT FILMS M. Isabel Alonso1, M. Garriga1, M. Campoy-Quiles1, A. R. Goñi1, 2, F. Hetsch3, S. V. Kershaw3, A. L. Rogach3, A. Bejaoui3, C. H. To3, Y. Foo3, J. A. Zapien3

1 Campus de la UAB, Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, Spain

2 ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain 3 City University of Hong Kong, Department of Physics and Materials Science and Centre for

Functional Photonics (CFP), Hong Kong SAR isabel.alonso@icmab.es Brightly emitting solution-grown colloidal quantum dots (QDs) of II-VI compounds offer great potential for optoelectronic and photonic devices. In this contribution, we report on the investigation by spectroscopic ellipsometry (SE) of films containing Cd(1-x)Hg(x)Te alloy QDs which were fabricated from binary CdTe QDs grown by an aqueous synthesis process followed by an ion-exchange step in which Hg2+ progressively replace Cd2+ ions [1]. Films were prepared for SE using three different techniques on glass and/or silicon substrates using drop cast (DC), layer-by-layer (LBL), and spin coating (SC) depositions. The contribution of the QDs to the measured ellipsometric spectra is extracted by fitting the data using standard multilayer and effective medium models that include surface roughness effects. We used DC and LBL to achieve films where the QDs are the main film constituent which to a large extent simplifies the retrieval of the QD optical properties. However DC results in large thickness non uniformities while LBL presents either small thickness or large bulk void ratio and surface roughness. In fact, for one LBL step the thickness measured by ellipsometry was ~3 nm in agreement with the expected nanoparticle size ~2.5 nm, while multiple LBL steps (up to 8 steps) results in exponential thickness increase which was confirmed by AFM measurements. We note that film assembly using LBL has been reported to be sensitive to pH and can result in exponential film growth accompanied by large surface segregation [2]. For SC films several polymer matrices were used which resulted on different concentrations of QDs. The relationship of the dielectric function of the QDs retrieved from these studies to that of the corresponding II-VI counterparts will be presented and discussed.

[1] Gupta S, Zhovtiuk O, Vaneski A, et al., Part. Part. Syst. Charact. 30, 346 (2013). [2] Choi I, Suntivich R, Plamper FA, et al., J. Am. Chem. Soc. 9592 (2011).

Measured and fitted ellipsometric spectra for angles of incidence from 55° to 75° taken at the layer-by-layer sample with nominally 1 layer. The best fit value of the thickness for this layer is 3 nm which is consistent with the slightly smaller nanoparticle size estimated to be ~2.5 nm. The obtained dielectric function is shown as an inset.

P38 MODELING OF DIELECTRIC RESPONSE OF HAFNIA FILMS Daniel Franta1, 2, David Nečas1, 2, Ivan Ohlídal1

1 Masaryk University, Faculty of Science, Department of Physical Electronics, Kotlářská 2, Brno, Czech Republic

2 Masaryk University, CEITEC - Central European Institute of Technology, RG Plasma Technologies, Kotlářská 2, Brno, Czech Republic

franta@physics.muni.cz Optical characterization of hafnia thin films is complicated by the fact that material structure tends to change from amorphous to polycrystalline phase during the growth, leading to a refractive index profile. The mixed phase cannot be modeled using the effective medium approach (EMA) with a precision sufficient for optical industry. Furthermore, the EMA does not preserve Kramers-Kronig consistency of the dielectric function and violates the sum rule. However, a dispersion model which describes the dielectric response of non-pure phases using only a minimum number of parameters is necessary. The presented model, although internally containing hundreds of parameters describing electronic and phonon excitations in the material, offers to possibility to describe hafnia using only the following material parameters: degree of crystallinity, density of nanopores, stoichiometric ratio and concentration of impurities. The model was constructed on the basis of ellipsometric and spectrophotometric measurements in a wide spectral range (0.009-8.7 eV) and it utilizes the Thomas-Reiche-Kuhn sum rule for the calibration of individual excitations.

Results of characterization of selected hafnia films deposited at different temperatures and exhibiting different degrees of crystallinity: (a) transmittance data in far IR region; (b) ellipsometric data in vacuum UV region; (c) obtained extinction coefficient in the region of phonon absorption; (d) obtained extinction coefficient in the region of valence-to-conduction electronic excitations.

P39 SURFACE LAYERS OF ZnMgRe QUASICRYSTALS Saulius Tumėnas1, V. Karpus1, R. Kondrotas1, A. Eikevičius1, S. Paurazaitė1, H. Arwin2

1 Center for Physical Sciences and Technology, Goštauto 11, LT-01108 Vilnius, Lithuania 2 Linköping University, SE-58183 Linköping, Sweden

saulius.tumenas@ftmc.lt We present results of spectroscopic ellipsometry (SE) and X-ray photoemission spectroscopy (XPS) studies of the natural surface layers of icosahedral ZnMgRE (RE = Y, Ho, Er) single-grain quasicrystals. Samples were grown by the liquid-encapsulated top-seeded solution-growth method [1] and naturally oxidized under normal atmospheric ambient. The spectroscopic ellipsometry measurements in the spectral range 0.73–6 eV were carried out by the dual rotating compensator ellipsometer RC2 (J. A. Woollam Co, Inc.,) in steps of 1 nm at 50°, 60°, and 70° of the incident angle. The XPS measurements were carried out by PHI VersaProbe II spectrometer (Physical Electronics, Chanhassen, MN) equipped with Al K(alpha) (1.487 eV) X-ray source. Experimental spectra of the ellipsometric parameters show that the optical response of naturally oxidized ZnMgRE quasicrystals manifests a pronounced oscillating dispersion and a strong dependence on the incident angle. The pronounced interference pattern allowed for a reliable determination of the surface layers optical parameters. In the analysis of the SE data, the gradient effective-medium approximation (EMA) model was used taking into account mixtures of Zn, Mg and RE oxides with the bulk material. The determined widths of the ZnMgY and ZnMgEr natural surface layers agree with the XPS data, which show them to be of 240 nm and 60 nm, respectively. The XPS depth profiles of atomic composition show that the ZnMgRE natural surface layers are not uniform. They start with the outer oxide layer, the relative concentration of oxygen in which is of about 50%. In the inner part of the layer, the oxygen concentration gradually decreases. The results of SE analysis qualitatively agree with those of XPS for the atomic composition of the surface layers.

[1] Langsdorf and W. Assmus, J. Cryst. Growth 192, 152 (1998).

P40 ANISOTROPIC DIELECTRIC FUNCTION AND EFFECTIVE ELECTRON MASSES OF RUTILE SnO2 Rüdiger Goldhahn1, Christian Lidig1, Karsten Lange1, Maciej Neumann2, Norbert Esser2, Mark E. White3, Min-Ying Tsai3, Oliver Bierwagen3, 4, James S. Speck3, Martin Feneberg1

1 Otto von Guericke Universität Magdeburg, Institut für Experimentelle Physik, Germany 2 Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Berlin, Germany 3 University of California, Santa Barbara, USA 4 Paul-Drude-Institut, Berlin, Germany

ruediger.goldhahn@ovgu.de Generalized spectroscopic ellipsometry is applied in order to determine the anisotropic optical response of rutile SnO2 spanning the range from phonon frequencies up to interband transitions, i.e. from 0.04 eV up to 20 eV, respectively. The results were obtained on several molecular-beam epitaxy grown films grown on (110) TiO2 and on r-plane Al2O3 substrates. The SnO2 layers have their optical axis in plane or inclined, respectively. After modeling the optical response of the layer stack and taking surface roughness into account, the full anisotropic dielectric function is extracted and compared to recent theoretical calculations. It turns out that electron-hole interaction influences the dielectric function up to 20 eV resulting in a pronounced redshift and redistribution of oscillator strength of features related to van Hove singularities. The data emphasize a band gap value for SnO2 of approx. 3.5 eV at room temperature. On a series of n-type doped SnO2:Sb layers, the plasmon-longitudinal optical phonon coupling was studied as a function of carrier concentration. The rutile crystal allows three phonon-polariton pairs for the electric field vector perpendicular to the optical axis yielding four plasmon-phonon coupled mode branches. In contrast, for the electric field vector parallel to the optical axis only two plasmon-phonon coupled modes are observed. Carrier dependent effective electron masses are achieved and will be discussed in detail.

P41 ELLIPSOMETRIC STUDY OF RELAXOR FERROELECTRIC PbSc0.5Nb0.5O3 FILMS Dagmar Chvostova, T. Kocourek, M. Jelinek, A. Dejneka, M. Tyunina Academy of Sciences of the Czech Republic, Institute of Physics, Na Slovance 2, 182 21 Prague 8 University of Oulu, Czech Republic Microelectronics and Materials Physics Laboratories, P. O. Box 4500, FI-90014 Oulun yliopisto, Finland chvostov@fzu.cz Thin films of relaxor ferroelectrics have a good potential for applications based on the coupling of photo-stimulated phenomena to other functional properties. However, optical properties of such films are poorly explored. Here we report on ellipsometric studies of optical properties of epitaxial PbSc0.5Nb0.5O3 (PSN) films performed in 0.8 – 8.9 eV spectral range. PSN films with thickness of ~(10 – 100) nm were grown by pulsed laser deposition onto SrTiO3 (001), DyScO (011), and MgO (001) single-crystal substrates. Perovskite structure of the PSN films was confirmed by XRD measurements. We acquired Psi and Delta angles values on a rotating-analyzer J. A. Woollam spectroscopic ellipsometer. The measured spectra were analyzed using a WVASE32 software package. The dielectric functions of the PSN films were extracted using a least squares regression analysis and an unweighted error function to fit the experimental ellipsometric spectra to an optical model consisting of a stack of semi-infinite substrate, homogenous film, surface roughness, and ambient air. The dielectric function analysis for the initial fit was based on four parametrized semiconductor oscillators. We also compared this model with the multioscillator model based on five Gaussian broadened oscillators, widely used for perovskite oxides. After initial values of the optical properties and thicknesses were determined, the thicknesses were fixed and the numerical inversion was used to extract the optical constants for PSN films directly from the measured spectra. Such procedure allowed us to obtain more accurate values of the optical constants in the near-bandgap region. The energies corresponding to maxima in the dielectric functions and the absorption coefficient, near-bandgap transitions, and bandgaps vary by ~0.1 – 0.5 eV in the films. The reason of such difference is probably connected to the local structure of the grown PSN films and is a subject of the future study.

P42 OPTICAL PROPERTIES OF HfO2 ANALYSED USING FIRST PRINCIPLE CALCULATIONS Pavel Ondračka1, 2, 3, David Holec1, Daniel Franta2, 3, Marek Eliác

2, 3, Lenka Zajíčková2, 3

1 Montanuniversität Leoben, Department of Physical Metallurgy and Materials Testing, Franz-Josef-Straße 18, Leoben A-8700, Austria

2 Masaryk University, Faculty of Science, Kotlářská 2, 611 37 Brno, Czech Republic 1 Masaryk University, CEITEC - Central European Institute of Technology, Kotlářská 2, 611 37

Brno, Czech Republic pavel.ondracka@gmail.com Hafnium dioxide is often used as optical coating (interference filters, anti-reflective coatings, mirrors etc.) in UV, visible and infrared range. In the present work, the dielectric response of two HfO2 crystalline allotropes, monoclinic and cubic, is calculated using the density functional theory approach. The linearized augmented plane wave method as implemented in the WIEN2k code together with the recently developed modified Becke-Johnson exchange-correlation potential allow for precise calculation of electronic structures including band gaps [1]. The first principle calculations also enable to identify electron transitions contributing to the individual peaks of the dielectric response function. The dielectric function calculated from the first principles is compared with the dielectric function obtained from the fitting of optical measurements on polycrystalline HfO2 films. The experimental data in the range from vacuum UV to far infrared include ellipsometric and spectrophotometric measurements. The complex dispersion model employed for the fitting is based on the Thomas-Reiche-Kuhn sum rule [2] and describes HfO2 by material parameters such as degree of crystallinity, density of nanopores, stoichiometric ratio and concentration of impurities. The detailed description of the dielectric response model for HfO2 films is presented elsewhere [3]. Polycrystalline HfO2 films often contain relatively high fraction of amorphous phase, which may be preferable to the polycrystalline form, e.g. due to the absence of grain boundaries. Therefore, an amorphous HfO2 structure is modeled within the framework of the simulated annealing technique using ab initio molecular dynamics and resulting optical properties are also discussed.

[1] F. Tran, P. Blaha, Phys. Rev. Lett. 102, 226401 (2009) [2] D. Franta, D. Nečas, L. Zajíčková, Thin Solid Films 534 (2013) 432-441 [3] D. Franta, D. Nečas, I. Ohlídal, Modeling of dielectric response of hafnia films, submitted to

WSE2014

Imaginary part of nonzero components of monoclinic HfO2 dielectric tensor

P43 OPTICAL PROPERTIES OF NANOFILMS OF WIDE BANDGAP BaTiO3 Ekaterina Chernova1, D. Chvostova1, T. Kocourek1, M. Jelinek1, V. Trepakov1, A. Dejneka1, M. Tyunina2

1 Academy of Sciences of the Czech Republic, Institute of Physics, Na Slovance 2, 182 21 Prague 8, Czech Republic

2 University of Oulu, Microelectronics and Materials Physics Laboratories, P. O. Box 4500, FI-90014 Oulun yliopisto, Finland

chernova@fzu.cz A good potential of wide bandgap perovskite-type ferroelectrics for applications in thin-film photonic and optoelectronic devices stimulates studies of optical properties of ferroelectric thin films. Here optical properties of BaTiO3 films with thickness of 4 - 100 nm were studied by spectroscopic ellipsometry in the 0.74 - 9 eV spectral range. BaTiO3 films were grown by pulsed laser deposition on single-crystal (001) SrTiO3 substrates. Perovskite structure of the BaTiO3 films was confirmed by XRD measurements. Psi and Delta angles were measured with rotating-analyzer J. A. Woollam VUV spectroscopic ellipsometer. The measured spectra were analyzed using a WVASE32 software package. The dielectric functions of the BaTiO3 films were extracted using a least squares regression analysis and to fit the experimental ellipsometric spectra to an optical model consisting of a stack of semi-infinite substrate, homogenous film, surface roughness, and ambient air. The dielectric function analysis for the initial fit was based on combination of 6 parameterized semiconductor oscillators. After initial values of the optical properties and thicknesses were determined, the thicknesses were fixed and the numerical inversion was used to extract the optical constants for BaTiO3 films directly from the measured spectra. Such procedure allowed us to obtain more accurate values of the optical constants in the near-bandgap region. Compared to bulk crystal BaTiO3, dramatic changes in the dielectric functions, near-bandgap transitions, and bandgaps of the nanofilms are revealed.

P44 COMPOSITIONAL INDUCED CHANGES IN OPTICAL RESPONSE OF SI-DOPED TITANIUM DIOXIDE Pavel Ondračka1, 2, 3, David Holec1, Daniel Franta2, 3, Eva Kedroňová2, 3, Stéphane Elisabeth4, Antoine Goullet4, Lenka Zajíčková2, 3

1 Montanuniversität Leoben, Department of Physical Metallurgy and Materials Testing, Franz-Josef-Straße 18, Leoben A-8700, Austria

2 Masaryk University, Faculty of Science, Kotlářská 2, 611 37 Brno, Czech Republic 3 Masaryk University, CEITEC - Central European Institute of Technology, Kotlářská 2, 611 37

Brno, Czech Republic 4 Université de Nantes, Institut des Matériaux Jean Rouxel (IMN), UMR CNRS 6502, 2 rue de

la Houssinière, BP 32229, 44322 Nantes Cedex 3, France pavel.ondracka@gmail.com s TiO2 thin films are good candidates for designing optical integrated waveguides or optical devices such as filters or resonators due to their high refractive index and low absorption in the visible range. However, they grow in columnar structure and have a relatively low band gap. Mixed TixSiyOz materials open new possibilities in overcoming some of the limitations imposed by TiO2 material. In the present work, the variation of SixTi(1-x)O2 optical constants caused by changed Si concentration are examined by employing Density Functional Theory. Special Quasirandom Structure method is used to generate structural models of SixTi(1-x)O2 disordered states for x = 0.0625, 0.125, 0.1875, and 0.25 for anatase and rutile phases. These initial supercells are structurally optimized (i.e. optimized with respect to the cell shape, size, and atomic positions) using the Vienna Ab initio Simulation Package. Optical constants of the resulting structures are calculated by the linearized augmented plane wave method as implemented in the WIEN2k full potential all electrons code together with the recently developed modified Becke-Johnson exchange-correlation potential allowing precise prediction of electronic structure and band gap. The predicted trends of the optical properties are further analyzed in order to identify transitions contributing to individual peaks. The calculated dielectric function is compared to the experimental data obtained by fitting the optical measurements (ellipsometry, spectrophotometry) carried out on TiO2 films containing rutile and anatase phases and available TixSiyOz films prepared by plasma enhanced chemical vapor deposition.

Dielectric function comparison of undoped TiO2 anatase and rutile allotropes

P45 FAST IN-SITU NULL ELLIPSOMETRY FOR STUDYING LASER EXCITED SOLID STATE SURFACES Zsolt Toth1, Zsuzsanna Pápa1, Judit Budai1, Anett Gárdián1, János Csontos1, Miklós Füle2

1 University of Szeged, Department of Optics and Quantum Electronics, H-6720 Szeged, Dóm tér 9., Hungary

2 University of Szeged, Department of Experimental Physics, H-6720 Szeged, Dóm tér 9., Hungary

ztoth@physx.u-szeged.hu Processing solid surfaces by pulsed lasers leads to heating or cooling times from femtoseconds to microseconds. These short excitations change the optical properties, which may influence the direction of processes, already during the processing laser pulse. Conventional rotating element and phase modulation ellipsometers are not capable to follow such short duration changes in material properties. In our work we deal with a pump and probe technique, which is combined with a single wavelength null ellipsometry. This technique enables us to follow the optical changes due to relaxation processes after a sub-ps laser pulse irradiation with a ps time resolution. Pulses from a distributed feedback dye laser (wavelength: 496 nm, pulse length 500 fs) are used for probe pulses. A part from these pulses is frequency doubled and amplified in a KrF excimer laser (wavelength: 248 nm, pulse length: 500 fs) [1]. These UV pulses are used as pump pulses. In our first test experiments the UV pump pulses are focused to a line, onto a <100> silicon surface by a fused silica cylindrical lens. The arrival of pump pulse is immediate at the surface, because its angle of incidence is 0°. The same area is irradiated with the probe pulses with a preset delay, using angles of incidences between 45° and 60°. Therefore the probe pulse scans the surface with a velocity defined by the speed of light and the angle of incidence. As the pump pulse heats up the Si surface the reflected probe intensity increases. In this way temporal reflectivity change of the surface can be converted to a spatial modulation of the intensity of the probe pulse. Introducing into the beam path the polarizing elements in a Polarizer - Sample - Compensator - Analyzer (PSCA) configuration null ellipsometry can be performed. By setting nulling condition, the transient index of refraction and absorption values has been determined.

[1] S. Szatmári, Applied Physics B 58 (1994) 211.

P46 OPTICAL PROPERTIES OF NIOBIUM-DOPED TiO2-X – A COMPARISON OF SPECTROSCOPIC ELLIPSOMETRY AND SPECTROPHOTOMETRY Johanna Reck, S. Seeger, M. Weise, R. Mientus Optotransmitter – Umweltschutz – Technologie e.V., 12555 Berlin reck@out-ev.de Doped and undoped titanium dioxide (TiO2) films are of great interest due to a variety of applications, esp. for photocatalytic coatings and as an indium free transparent conductive electrode material. Advantages of TiO2 are its abundance, non-toxicity and high chemical stability. The combination of high transparency (~ 90% in the VIS region) and low resistivity (> 3*10-4 Ωcm) [1] of doped TiO2 is suitable for substituting tin-doped indium oxide (ITO). For the usage as TCO the distinct knowledge of the optical properties (e.g. refractive index n, ext. coefficient k, band gap energy Eg) is essential. The aim of this work is the comparison of different approaches for the optical modelling of spectroscopic ellipsometric (Ψ and Δ) and photometric (T and R) measurements. The films were prepared by reactive magnetron sputtering from a metallic Ti (94 at%) / Nb (6 at%) target. After thermal annealing the films reach electrical resistivities from 3*10-2 to 1*10-3 Ω cm and transparencies of 75% to 82%. Ψ and Δ were measured at three angles of incidence in the spectral range of (280-800) nm with a SE850 (SENTECH). The spectra were modelled with SpectraRay3 (SR3, SENTECH) using two band gap models (Cody [2], Tauc Lorentz (TL) [3], resp.). The optical model consists of three layers, 1. substrate, 2. TiO2-x:Nb film and 3. roughness modelled by EMA of Maxwell Garnett. Results from Ψ and Δ are compared with those from fitted T and R (measured with a Cary 5e, Varian) in Scout (W. Theiss) using TL and OJL [4], resp.. Eg depend on the investigation method and the choice of model but only slightly on resistivity. Optical thickness is consistent to stylus profilometry for all optical model approaches.

[1] Yamada, N., et al., TSF, 2010. 518(11): p. 3101-3104. [2] Ferlauto, A.S., et al., JAP, 2002. 92(5): p. 2424-2436. [3] Jellison, G.E., Modine F. A., APL, 1996. 69(3): p. 371-373. [4] O'Leary, S., et al., JAP, 1997. 82(7): p. 3334 - 3340. [5] Hanaor, D.O.H., J.Mat.Sci. (2011) 46: p. 855–874.

T & R and Ψ & Δ deliver different Eg, which also depend on the model (-T & R, OJL + Drude, Scout; -T & R, TL + Drude, Scout; -T & R, TL, Scout; Ψ & Δ, TL + Drude, SR3; Ψ&Δ, TL, SR3, Eg anatase TiO2 [5]). n does not vary that strong. ♦ Transmission (7° incidence) is almost constant. Deviation and MSE are not comparable but rate the models within the software.

P47 IDENTIFICATION OF SCATTERING MECHANISMS IN MOCVD-GROWN AlGaN/GaN HIGH ELECTRON-MOBILITY TRANSISTORS BY TEMPERATURE-DEPENDENT THZ OPTICAL HALL-EFFECT AND COMPARISON WITH MOBILITY CALCULATIONS St. Schöche1, V. Darakchieva2, P. Kühne1, J.-T. Chen2, U. Forsberg2, E. Janzén2, N. Ben Sedrine2, C. M. Herzinger3, J. A. Woollam3, Mathias Schubert1, T. Hofmann1

1 University of Nebraska-Lincoln, Department of Electrical Engineering and Center for Nanohybrid Functional Materials, USA

2 Linköping University, Department of Physics, Chemistry and Biology, IFM, Linköping, Sweden

3 J. A. Woollam Co., Inc., 645M Street, Suite 102, Lincoln, Nebraska 68508, USA schoeche@huskers.unl.edu High electron mobility transistors (HEMT) utilize the formation of a two-dimensional electron gas (2DEG) at the interface between GaN and AlGaN due to different spontaneous polarization. The mobility of the 2DEG electrons and therefore device performance is limited by several scattering mechanisms. For 2DEGs in GaN these are LO phonon scattering, piezoelectric and deformation potential scattering, and scattering at dislocations, interfaces and charged background impurities. Device optimization requires knowledge of the relationship between structural properties and scattering mechanisms. We utilize the THz optical Hall effect (generalized ellipsometry with applied magnetic field) to determine the temperature dependent 2DEG parameters in four MOCVD-grown HEMTs. In this set, the growth temperature of the GaN was systematically varied while other deposition parameters were kept identical. XRD and AFM indicate comparable structural properties, while SIMS shows a systematic decrease of carbon contamination in the GaN layer with increasing growth temperatures, typical for MOCVD-grown samples. At low temperatures, a strong dependence of the mobility on the growth temperature of the GaN layer is found from the THz optical Hall-effect analysis, while effective mass and sheet charge concentration remain nearly constant between the samples. Scattering theories are applied in order to match the experimentally determined temperature dependent mobility. At low-temperatures only three scattering processes contribute significantly to the total mobility, of which only the background impurity scattering should change between the different samples investigated here. The theoretical impurity concentrations necessary to result in the experimental mobility values resemble the carbon concentrations found by SIMS. This indicates that background impurity scattering related to the carbon contamination is the performance limiting mechanism in our MOCVD grown sample set.

Determined (symbols) temperature-dependent mobility of the 2DEG in a MOCVD-grown HEMT structure in comparison with theoretical calculations for the dominant scattering mechanisms in this sample, scattering mechanisms taken into account are deformation potential (DP), piezoelectric (PZ), optical phonon (LO), background impurity (BI), interface roughness (IFR), and dislocation scattering (Dis)

P48 IN-SITU INFRARED SPECTROSCOPIC ELLIPSOMETRY ON TEMPERATURE-RESPONSIVE COPOLYMER BRUSHES Annika Kroning1, Andreas Furchner1, Michael Seeber2, Igor Luzinov2, Karsten Hinrichs1

1 Leibniz Institut für Analytische Wissenschaften – ISAS – e.V., Albert-Einstein-Str. 9, 12489 Berlin

2 Clemson University, School of Materials Science and Engineering, Clemson, South Carolina 29634-0971

annika.kroning@isas.de Functional polymer interfaces are thin layers (<30 nm) of responsive polymers and have been studied intensively over the past years [1]. Due to the densely end-grafted polymer chains on the substrate the chains are forced to stretch away from the surface like bristles on a brush. In such a system the chains respond collectively to an external stimulus, e.g. a change in temperature. In this study, a temperature-responsive polymer – Poly (N-isopropyl acrylamide) [PNIPAAm] – is used. Its response takes place around the lower critical solution temperature (LCST) of 32° C, therefore it is of special interest for biomedical applications. The brushes were synthesized by the “grafting to” method. A copolymer consisting of PNIPAAm and an anchoring polymer (Poly (glycidyl methacrylate), [PGMA]) was grafted in one step instead of the traditional 2-step synthesis, where the anchoring layer is grafted first, followed by the functional polymer. Infrared Spectroscopic Ellipsometry (IRSE) is used to study the structure and responsive behavior of these interfaces. We are particularly interested in the polymer-polymer and polymer-water interactions and how these interactions change when the stimulus is applied. A specially designed in-situ cell enables us to probe the solid-liquid interface of the polymer in contact with solution [2].

[1] Chen et al., Progress in Polymer Science 2010, 35, 94-112. [2] Furchner et al., Thin solid films 2013, 541, 41-45.

Scheme of the switching behavior of a PNIPAAm brush in water.

P49 ANOMALOUS OPTICAL BEHAVIOR OF METAL-POLYMER NANOCOMPOSITES Corentin Guyot, Michel Voué Université de Mons Physique des Matériaux et Optique 20, place du Parc, B-7000 Mons (Belgium) corentin.guyot@umons.ac.be Metal nanoparticles (NPs) play a central role in the development of nanotechnology-based optical devices. Their optical properties are strongly influenced by their shape and size but also by the dielectric properties of their environment, in particular when the NPs are embedded in a dielectric matrix. A wide range of experimental methods is available for the synthesis of such materials. Besides the methods involving the synthesis of the NPs in a liquid medium, with or without further coating to prevent their aggregation and their dispersion in a solid phase, NPs can be synthesized in situ following the irradiation or the thermal annealing of the solid phase. Although the first approach has an evident advantage of leading to the synthesis of NPs with wide ranges of shapes, size, etc., the synthesis methods of the second category are usually simpler (one-pot synthesis) but their mechanism is today not fully understood although being the subject of an increasing number of publications. In this study, we investigated using spectroscopic and imaging ellipsometry in the visible spectral domain the optical properties of polyvinyl alcohol/silver nanocomposites. The ellipsometric spectra were modeled by describing the nanocomposite layer by a Cauchy law with a Lorentzian absorption peak to account for the plasmon resonance. The distribution of optical resonance parameters of more than 90 samples was analyzed using multivariate statistical methods (principal components analysis and support vector machines), allowing us to conclude that significant differences exist between thin (less than 30 nm) and thick (more than 300 nm) nanocomposite films. As expected, the amplitude of the resonance peak (A) is strongly correlated with the silver content but the correlation between the width (Gamma) and the position of the peak (L0) are different for thick and thin films. This work is supported by the National Fund for Scientific Research of Belgium (FRFC project n°1926111).

Statistical correlation between the L0 and Gamma parameters of the resonance peak. Red and cyan circles correspond to high and low silver doping levels, respectively.

P50 SWELLIPSOMETRY IN TWENTE: MEASURING POLYMER SWELLING BY IN-SITU ELLIPSOMETRY Wojciech Ogieglo1, Emiel J. Kappert2, Michiel Raaijmakers2, Herbert Wormeester3, Matthias Wesslin4, Nieck E. Benes2

1 University of Twente, Faculty of Science and Technology and MESA+ Institute of Nanotechnology, Membrane Science and Technology, P.O. Box 217, 7500 AE Enschede, The Netherlands

2 University of Twente, Faculty of Science and Technology and MESA+ Institute of Nanotechnology, Inorganic Membranes, P.O. Box 217, 7500 AE Enschede, The Netherlands

3 University of Twente, Faculty of Science and Technology and MESA+ Institute of Nanotechnology, Physics of Interfaces and Nanomaterials group, P.O. Box 217, 7500 AE Enschede, The Netherlands

4 RWTH Aachen University, Chemical Process Engineering, Turmstr. 46, 52056 Aachen, Germany

n.e.benes@utwente.nl Thin and ultra-thin (<100 nm) polymer films are frequently used in important technological areas, including coatings, barrier and membrane applications. In these areas the films are frequently exposed to interacting penetrants. The interactions may significantly change equilibrium and dynamic properties of the thin film systems, thereby influencing their performance. In addition, it is known that the reduction of polymer film thickness below about 100 nm may result in the manifestation of, so called, nano-confinement effects. This term relates to the pronounced departure of the ultra-thin polymer properties from those of the bulk. In-situ spectroscopic ellipsometry is a powerful technique for monitoring dynamic changes in properties of thin films in contact with penetrants. This non-intrusive technique allows for very high precision, accuracy, and temporal resolution. In this contribution we show several examples in which the potential of the technique is utilized. The examples include studies on temperature-induced transitions of penetrant diffusion mechanisms in the vicinity of glass transition, probing surface diffusion in ultra-thin glassy films, and thin film composite membrane behavior under non-equilibrium permeation conditions.

P51 OPTICAL PROPERTIES OF HUMAN DENTAL ENAMEL – AN APPLICATION OF SPECTROSCOPIC IMAGING ELLIPSOMETRY A. Kiesow1, C. Röling2, Peter H. Thiesen2

1 Fraunhofer-Institut für Werkstoffmechanik IWM, Walter-Hülse-Str. 1, D-06120 Halle, Germany

2 Accurion GmbH, Stresemannstr. 30, D-37079 Göttingen, Germany pt@accurion.com Dental enamel is one of the major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. To answer a number of questions, like aesthetics aspects of dental restorations, efficiency of tooth cleaning or the quantification of discoloration by adsorption of chromogens from tobacco, coffee, or tea, the optical characterization of human dental enamel is of high scientific and technical relevance. In this work, human molars and incisors were cut; cross sections were embedded in polymer resin, ground and polished. The samples were characterized with an imaging ellipsometer nanofilm_ep3se. Delta/Psi wavelength spectra (UV/VIS) were performed at distinctive regions of interest (ROI). Spectra of Delta and Psi were recorded. Additional, ellipsometric contrast micrographs as well as Delta and Psi-maps were performed to determine the lateral distribution of the optical properties of human dental enamel. For illustration, a human incisor is displayed in the figure. The work shows exemplarily the capability of imaging ellipsometry for a detailed investigation of the optical properties of biological materials.

Ellipsometric contrast micrographs and Psi-maps of dental enamel at different positions of a human incisor.

P52 SPECTROSCOPIC ELLIPSOMETRY OF SELF-ASSEMBLED MONOLAYERS: INTERFACE EFFECTS. THE CASE OF PHENYL SELENIDE SAMS ON GOLD Maurizio Canepa1, Giulia Maidecchi1, Chiara Toccafondi1, 2, Ornella Cavalleri1, Mirko Prato2, Vijay Chaudhari2, 3, Vladimir A. Esaulov4

1 University of Genova, Department of Physics, Italy 2 IIT, Genova, Italy 3 North Maharashtra University, Department of Nano Science and Technology, Jalgaon, India 4 Université Paris Sud, Institut des Sciences Moléculaires d’Orsay (ISMO), Orsay, France

canepa@fisica.unige.it This work focuses on the quantitative application of spectroscopic ellipsometry to the study of optical properties and thickness of self-assembled monolayers (SAMs) of phenyl selenide deposited from the liquid phase on gold. STM, XPS and cyclic voltammetry measurements provide additional chemical and morphological characterization of the SAMs. While routine ellipsometry analysis of SAMs often relies on the film-induced dΔ change in the Δ ellipsometric angle and discards SAM–substrate interface effects, the present data show a distinctive behaviour of the dΨ data that we assign to interface effects [1], stronger than those previously found for related densely packed alkanethiol SAMs [2, 3]. An inaccurate modelling of the variations in Ψ related to the nano-structured SAM–substrate interface leads to a large overestimation of the film thickness. A simple model, which takes into account an effective approximation for the interface layer between the film and the substrate, and the molecular optical absorptions, provides a good agreement between the data and a reliable thickness estimate of the SAM [1].

[1] M. Canepa, G. Maidecchi, C. Toccafondi, O. Cavalleri, M. Prato, V. Chaudhari, and Vladimir A. Esaulov, Phys. Chem. Chem. Phys., 2013,15, 11559

[2] M. Prato, R. Moroni, F. Bisio, R. Rolandi, L. Mattera, O. Cavalleri and M. Canepa, J. Phys. Chem. C. 112 (2008) 3899

[3] H. Hamoudi, Z. Guo, M. Prato, C. Dablemont, W. Q. Zheng, B. Bourguignon, M. Canepa and V. A. Esaulov, Phys. Chem. Chem. Phys., 2008, 10, 6836–6841

P53 PROPERTIES OF THE DIELECTRIC TENSOR OF α-3,4,9,10-PERYLENE TETRACARBOXYLIC DIANHYDRIDE IN THE OPTICAL SPECTRAL RANGE M. Isabel Alonso1, M. Garriga1, J. O. Ossó2, F. Schreiber3, R. Scholz4

1 Campus de la UAB, Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, Spain

2 Campus de la UAB, MATGAS Research Center, 08193 Bellaterra, Spain 3 Universität Tübingen, Institut für Angewandte Physik, 72076 Tübingen, Germany 4 Technische Universität Dresden, Institut für Angewandte Photophysik, 01062 Dresden,

Germany isabel.alonso@icmab.es The compound 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) is considered an archetypical organic semiconductor because of its favorable properties. From the structural point of view, the planar PTCDA molecules crystallize into stacks of nearly planar sheets of molecules arranged in herringbone pattern. In both known polymorphs the molecular plane is the (102) crystal plane, relevant to ordered film growth. The small stacking interplanar distance of around 0.32 nm brings about a rather strong intermolecular π-electron overlap. Hence, from the point of view of its electronic structure, PTCDA is also a model example to understand the functional electronic performance of this class of materials. In this study, we used bulk samples of α-PTCDA to measure the dielectric tensor of this monoclinic crystal in the spectral range between 1.4 and 5.1 eV. Knowledge of the anisotropic optical functions is required as input for device modeling as well as to provide insight into spectroscopic features related to the electronic structure of the material. Spectroscopic ellipsometry measurements of tanΨ and cosΔ obtained on three different surfaces of the crystal were combined and analyzed using a general scheme in which the exact ellipsometric equations are solved numerically within a 4x4 transfer matrix algorithm. From this analysis we derive the diagonalized tensor components εX, εY, and εZ, where Y is the monoclinic axis. We detect crosstalk between components X and Z, in the plane perpendicular to the Y axis, a distinctive trait of monoclinic symmetry. By this effect three main structures appear in the weak component (εX in this case) when a resonance effect with the stronger εZ component occurs. Additionally we observe different orientations for the principal axes of the real and imaginary dielectric function tensors. We will describe the general characteristics of the dielectric tensor, particularly in monoclinic systems, and explain the obtained results in α-PTCDA.

P54 SPECIFIC AND ASPECIFIC BONDING OF PROTEINS ON NTA SELF ASSEMBLY MONOLAYER ON GOLD STUDIED BY SPECTROSCOPIC ELLIPSOMETRY Ilaria Solano1, F. Gramazio1, L. Ianeselli2, P. Parisse2, O. Cavalleri1, M. Castronovo3, L. Casalis2, M. Canepa1

1 Universitá di Genova, Dipartimento di Fisica, Via Dodecaneso 33, Genova, Italy 2 Sincrotrone Trieste SCpA, I-34149 Trieste, Italy 3 University of Udine, Department of Medical & Biological Sciences, I-33100 Udine, Italy

solano@fisica.unige.it We present results on a work-in-progress Spectroscopic Ellipsometry (SE, 245-1700 nm) investigation about the functionalization of well-defined gold polycrystalline surfaces with Self-Assembled Monolayers (SAM) of Nitrilotriacetic acid (NTA) thiols. Our aim is to investigate aspecific and specific bonding of proteins at the functionalized surface. The possibility of recognizing the nature of the SAM-protein binding is a useful resource in the development of label-free biosensors. NTA SAMs are initially prepared in ethanol solution. Their thickness and optical properties are compared with those of long chain alkanethiols (e.g. C18), testifying the attainment of a compact thiolated SAM. Aspecific bonding was first investigated through the adsorption of Yeast Cytochrome c (YCC), a heme protein presenting strong absorption Soret bands in the UV-VIS region. Using the method of difference spectra [1, 2] we were able to evaluate the thickness and optical properties of the protein layer. Results are compared with our recent studies for adsorption of YCC on gold and silicon surfaces [3, 4]. In a second part of the study, Ni(II) ions are introduced to bind histidine tagged receptors, such as the Small Ubiquitine-like Modifier (SUMO) protein, to the NTA SAM to investigate the adsorption specificity. Each step of the preparation is characterized through in-situ (buffer) and ex-situ SE in order to follow the evolution of the thickness and optical properties of the sample. Further experiments and analysis of data are in progress to clarify the meaning of some interesting spectral features in the UV region which could be directly related to the specific Histidine-Ni(II) bond.

[1] B. Sanavio et al. ACS NANO 4 (2010) 6607-6616 [2] M. Prato et al., J. Phys. Chem. C. 112 (2008) 3899 [3] M. Prato et al., J. Phys. Chem. C 113, (2009) 20683 [4] C. Toccafondi, et al. J. Colloid. Interf. Sci. 364, (2011) 125 [5] C. Toccafondi et al. Thin Solid Films 543, 78-82 (2013)

P55 REAL-TIME DETECTION OF ANTIGEN-ANTIBODY INTERACTION USING TOTAL INTERNAL REFLECTION ELLIPSOMETRY Yu Ri Kang, J. S. Byun, J. C. Park, J. Choi, Y. D. Kim Kyung Hee University, Nano-Optical Property Laboratory and Department of Physics, Seoul, 130-701, Korea ydkim@khu.ac.kr The advance of highly sensitive biosensor is important for the study on the interaction mechanism among biomolecules such as antigen and antibody based on the biotechnology and medicine development. Typical analytic techniques are the gel electrophoresis using the mobility as the weight of molecules, fluorescent microscopy using attached fluorescent for labeling, and label free technique such as surface plasmon resonance (SPR) and spectroscopic ellipsometry (SE). The SE using two parameters can give more information of biomaterials than SPR which use only reflectance. However, biological application of SE is limited because of the complex optical modeling and relatively low sensitivity. To overcome these disadvantages, we developed the total internal reflection ellipsometry (TIRE) measurement system which combines high surface sensitivity of the SPR and the analytic ability of the SE. In this work, we studied the interaction between epidermal growth factor receptor (EGFR) protein and EGFR aptamer. EGFR exists on cell surface and control cell growth and division. EGFR research is important because the over-expression and over-activity of EGFR are the most common symptoms in a number of cancer patients. Improvement of effective EGFR protein detect techniques has a great potential for diagnosis of the cancer. Therefore, we performed experiment to detect the EGFR proteins by the reaction with the aptamer which is an oligonucleotide with high affinity and selectivity for various target compounds. We expect that our work can be used as a bio-sensor with high sensitivity and apply to various proteins, enzymes, and biomolecules.

Δ spectrum of SAM monolayer on Au film (dot) and WSC+NHS (solid), EGFR protein (dash) solution inject under the PBS buffer at AOI 70°.

P56 STUDY ON THE COLLAPSED ARACHIDIC ACID WITH VARIOUS COMPRESSION RATES BY IN-SITU IMAGING ELLIPSOMETRY Han Gyeol Park, S. Y. Hwang, T. J. Kim, J. Y. Kim, N. S. Barange, J. C. Park, Y. D. Kim Kyung Hee University, Nano Optical Property Laboratory and Department of Physics, Seoul, 130-701, Korea ydkim@khu.ac.kr In this research, in-situ imaging ellipsometry (IE) was used as a tool of monitoring the morphology of collapsed films of arachidic acid (AA) molecular layers at the air/water interface with various rates of molecular area compression. Due to inherently inhomogeneous collapsed monolayer, IE is a necessary method which can determine different optical properties with appropriate spatial resolution. All of the IE experiments were carried out at room temperature (20° C) and the incidence angle and the wavelength are set to 53.18° (Brewster angle at pure water) and 633 nm, respectively. To analyze the collapsed AA monolayer, we determined dielectric function of AA by conventional spectroscopic ellipsometry. We changed the rate of molecular area compression from 0.23 to 0.94 Ų/min and showed the IE images of multilayer domains and Langmuir isotherm in the figure. The changes of multilayer domains could be observed successfully by in-situ IE images. The structure of the collapsed films changes sensitively depending on the history of compression due to the collapse of the monolayer proceeding through metastable states away from equilibrium.

Langmuir isotherms and in-situ IE images at 9.5 Ų.

P57 SPECTROSCOPIC ELLIPSOMETRY CHARACTERIZATION OF PLASMONIC FILMS FOR SURFACE-ENHANCED SENSORS Dimitra. Gkogkou1, 2, 3, I. M. Weidinger1, P. Hildebrant1, K. Hinrichs2, N. Esser2, T. W. H. Oates2

1 Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße des 17. Juni 135,D-10623 Berlin (Germany)

2 ISAS—Institute for Analytical Sciences, Department Berlin, Albert-Einstein Str. 9, 12489 Berlin, Germany

3 School of Analytical Sciences Adlershof (SALSA), IRIS-Building, Adlershof, Unter den Linden 6, 10099 Berlin,Germany

dimitra.gkogkou@isas.de Localized surface plasmon resonances (LSPR) are the collective oscillations of the electron gas that occur upon resonant coupling with incident electromagnetic radiation. This phenomenon in noble metal nanoparticles (NPs) causes an electromagnetic field enhancement that leads to surface-enhancement of both Raman scattering (SERS) and Infrared (SEIRA) absorption. The LSPR spectral position can be controlled by variables such as the NPs' shape, size and distribution [2]. Surface-enhanced spectroscopic techniques play an important part in (bio)sensing, a field constantly developing with applications in areas such as biotechnology, medical diagnostics, security. This raises the demand for the development of label-free, hypersensitive, analyte-specific chemo- and bio-sensors. For this reason we aim to investigate the combination of noble metal NPs substrates, self-assembled monolayers and target molecules [1]. We present results of spectroscopic ellipsometry characterization of silver and gold island films prepared by evaporation. Ellipsometry measurements (SENTECH SE850) were performed in the DUV-Vis-NIR spectral range. The film thickness and peak wavelength of the LSPR are determined for films with varying deposition parameters. Self-assembled monolayers are prepared on the films and the SERS and SEIRA spectra are recorded, using confocal Raman and FTIR microscopy. The enhancement factors are determined for the deposition conditions and are correlated with the optical and structural properties of the films. The effects of oxidation on silver island films are also investigated.

[1] J. J. Feng, U. Gernert, P. Hildebrandt, and I. M. Weidinger, 'Induced Ser-Activity in Nanostructured Ag-Silica-Au Supports Via Long-Range Plasmon Coupling', Advanced Functional Materials, 20 (2010), 1954-61.

[2] T. W. H. Oates, H. Wormeester, and H. Arwin, 'Characterization of Plasmonic Effects in Thin Films and Metamaterials Using Spectroscopic Ellipsometry', Progress in Surface Science, 86 (2011), 328-76.

Ellipsometry data (imaginary part of the pseudodielectric function) showing the plasmon resonance changes for samples exposed to oxygen for the designated time. Right corner: Side view SEM of a silver metal island film (MIF) deposited on SiO2 by magnetron sputtering at room temperature. Scale bar is 100 nm.

P58 SPR ENHANCED DYNAMIC SPECTROSCOPIC ELLIPSOMETRY FOR STUDY OF MONOMERIC AND DIMERIC GRANULOCYTE COLONY STIMULATING FACTOR INTERACTION WITH RECEPTOR Z. Balevicius1, 3, Saulius Tumėnas1, L. Tamosaitis1, 2, I. Baleviciute2, A. Stirke1, A. Makaraviciute1, 2, A. Ramanaviciene2, A. Ramanavicius1, 2

1 State Research Institute Center for Physical Sciences and Technology, Savanoriu ave. 231, LT-01108 Vilnius, Lithuania

2 Vilnius University, Faculty of Chemistry, Naugarduko 24, 03225 Vilnius, Lithuania. 3 Vilnius Gediminas Technical University, Faculty of Electronics, Sauletekio 11, LT-10223

Vilnius, Lithuania zbalevicius@ar.fi.lt Recently, label-free optical biosensors have received a lot of attention due to their high sensitivity [1] and their ability to measure protein adsorption dynamics [2]. The in situ measurements are usually performed in order to obtain information about biochemical interaction of biomolecules at the solid-liquid interface [3, 4]. Total Internal Reflection Ellipsometry (TIRE) in its spectroscopic dynamic data acquisition mode is able to detect miniscule changes of the refractive index during the immobilization of various biomolecules with better accuracy than single wavelength ellipsometry due to the elimination of the non-linearity of the signal through regression analysis of spectroscopic ellipsometry data. Spectroscopic TIRE in its dynamic data acquisition mode has been applied for the in situ study of the interactions of monomeric (mGCSF) and dimeric (dGCSF) granulocite colony stimulating factor and its receptor (GCSF-R) which was immobilized on a thin gold layer. Regression results have shown that the account for signal non-linearity due to analysis of spectroscopic dynamic TIRE data has allowed us to detect small differences in association and dissociation times through the precise determination of the refractive index dispersion. Different binding models were applied in the study of monomeric (mGCSF) and dimeric (dGCSF) interaction with a monolayer of its receptor (GCSF-R) due to their distinctive changes of refractive index over time. Numerical calculations of Monte Carlo method have been used to reveal the real-time formation of mGCSF and dGCSF monolayers structure.

[1] V.G. Kravets et al., Nature Materials (2013) 1-6. [2] H. Arwin, Thin Solid Films 519 (2011) 2589–2592. [3] I. Baleviciute, et al., Biosensors and Bioelectron. 39 (2013) 170-176. [4] Z. Balevicius, et al., Thin Solid Films (2013), http://dx.doi.org/10.1016/j.tsf.2013.10.090

P59 BIOFUNCTIONALIZATION OF POLYMER BRUSHES WITH RGD PEPTIDES: AN ELLIPSOMETRIC STUDY Evmorfia Psarra1, 2, Ulla König1, Klaus-Jochen Eichhorn1, Manfred Stamm1, 2, Petra Uhlmann1

1 Leibniz-Institut für Polymerforschung Dresden e.V., Dresden, Germany 2 Technische Universität Dresden, Physical Chemistry of Polymer Materials, Dresden, Germany

psarra@ipfdd.de The main focus of this work is the surface biofunctionalization of ultra-thin, stimuli responsive polymer brushes grafted to model surfaces. Different polymer brushes either composed out of a pH responsive component, the Poly(acrylic) acid (PAA), and/or a temperature responsive material, the Poly(N-isopropyl acrylamide) (PNIPAAm) are used to investigate the Arg-Gly-Asp (RGD) peptide binding to the brush surface. Using PNIPAAm mixed with PAA polymer material in order to generate binary brushes will help to create smart surface coatings which are hiding or exposing their functionalities by changing the temperature from physiological (37° C) to room temperature. Binary brushes functionalized with cell-signaling molecules, can lead to intelligent stimuli-responsive bio-nanosurfaces, able to regulate cell adhesion and function. In particular, the cell signaling peptide incorporated in the binary PAA-PNIPAAm polymer brush system is the RGD tripeptide sequence. This RGD peptide sequence is the recognition sequences for integrins. Proteins that contain the RGD attachment site, together with the integrins (cell membrane proteins), that serve as RGD receptors, help cells to adhere to neighbor cells and/or to their extracellular environment. Ellipsometry is used in order to study the differences between covalently immobilized and physically adsorbed RGDs onto the brush surfaces. The ellipsometric data analysis of the RGD modified surface should give qualitative answers, regarding the presence of RGDs and quantitative, regarding the amount of the peptide in a certain surface area. Spectroscopic Ellipsometry is a very powerful surface analysis technique that gives answers to both of these questions. The primary use of this technique gives possibilities on monitoring and further controlling peptide attachment on polymer brushes. Here we are presenting our in situ spectroscopic ellipsometry results in terms of RGD immobilization versus RGD adsorption on PAA brush systems.

The RGD modified polymer binary brush shows temperature response. a) Cells are cultivated at physiological temperature on the PNIPAAm-PAA\RGD brush. At this temperature PNIPAAm is collapsed and RGDs are exposed to the cell membrane proteins (integrins), which anchor the cells to the brush surface. b) At room temperature the RGD functionalities are hidden and cells are released.

P60 IN SITU TEMPERATURE-DEPENDENT SPECTROSCOPIC ELLIPSOMETRY OF CONJUGATED SEMICONDUCTING MATERIALS Lukas Bernhauser1, Eric Daniel Głowacki1, Christoph Cobet2, Markus Scharber1, Kurt Hingerl2, Niyazi Serdar Sariciftci1

1 Johannes Kepler University of Linz, Physical Chemistry, Linz Institute for Organic Solar Cells (LIOS), A-4040 Linz, Austria

2 Johannes Kepler University of Linz , Zentrum für Oberflächen- und Nanoanalytik A-4040 Linz, Austria

lukas.bernhauser@jku.at We present our ellipsometric studies of organic semiconducting thin films, using the semiconducting polymer poly(3-hexylthiophene) (P3HT) as a standard. P3HT is being used as a semiconductor material, especially for solar cells, due to its high ordering after annealing. In particular we study temperature dependent order/disorder phase transitions in organic semiconductors. Herein temperature dependent measurements are used to study optical properties as a function of temperature, with the annealing-induced crystallization of P3HT as an illustrative example. Furthermore, we focused our investigations on high dielectric-constant hydrogen-bonded pigments such as indigos, quinacridones, and epindolidiones to determine the complex dielectric functions of these materials. We also show that this temperature-dependent method can be used to monitor chemical reactions occurring in thin organic films, including thermal cleavage of protection groups used for solution-processing hydrogen-bonded thin films.

P61 SWELLING BEHAVIOR OF THERMORESPONSIVE POLYMER BRUSH SYSTEMS BASED ON POLY(2-OXAZOLINE)S Stefan Adam1, 2, Klaus-Jochen Eichhorn1, Juan Carlos Rueda3, Manfred Stamm1, 2, Mathias Schubert4, Petra Uhlmann1

1 Leibniz-Institut für Polymerforschung Dresden e.V., 01069 Dresden, Germany, 2 Technische Universität Dresden, 01062 Dresden, Germany, 3 Pontificia Universidad Católica del Perú, Lima, Peru, 4 University of Nebraska-Lincoln, Lincoln, NE 68588, USA

adam-stefan@ipfdd.de Responsive polymer coatings or hydrogels came into the focus of research due to their capability of changing their physical and structural properties induced by changes in their environmental condition (e.g. temperature). Poly(2-oxazoline)s (POX), being structural isomers to polyacrylamides (e.g. poly(N-isopropylacrylamide), PNiPAAm) can exhibit a lower critical solution temperature (LCST) in aqueous solution. Moreover, the LCST can be tuned by adjusting the molar mass or by copolymerization with more hydrophilic/hydrophobic comonomers. Since POX are biocompatible, less likely to oxidative degradation compared to poly(ethylene glycol) [1] and show a smaller hysteresis of phase transition than PNiPAAm [2] this class of polymers reveals interesting properties for many applications, such as sensor systems or in biomaterials. A combinatorial Quartz Crystal Microbalance with Dissipation (QCM-D) and Spectroscopic Ellipsometry (SE) setup can be used to study quantitatively the swelling characteristics of polymer films [3] herein POX brushes prepared by the “grafting to” method using pre-synthesized polymers with functionalized end groups. For optical modeling an effective-medium-approach was applied and in QCM-D analysis the attached mass was evaluated by a viscoelastic model. The swelling behavior of POX brushes was compared to the phase transition of a corresponding aqueous polymer solution, determined by turbidity measurements. All POX, bearing 2-cyclopropyl-2-oxazoline moieties and varying ratios of 2-methyl-2-oxazoline (MeOXA) as hydrophilic comonomer, show sharp transition curves in aqueous solution. Increasing the amount of MeOXA shifts the LCST towards higher temperatures. In contrast, POX brushes exhibit a continuous reversible swelling over a wide temperature range. We acknowledge funding by DFG.

[1] B. Pidhatika et al., Biointerph., 7, 1 (2012). [2] R. Hoogenboom et al., Chem. Commun., 44, 5758-5760 (2008). [3] E. Bittrich et al., Biointerph., 5, 1-9 (2010).

P62 MOLECULAR ORIENTATION IN LIGHT ABSORBING THIN FILMS FOR ORGANIC SOLAR CELLS: CORRELATION OF THEORY AND EXPERIMENT O. Guskova1, C. Schünemann1, 2, Eva Bittrich1, K.-J. Eichhorn1, K. Walzer3, M. Levichkova3, S. Grundmann3, M. Stamm1, 2, J.-U. Sommer1, 2

1 Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany 2 Technische Universität Dresden, 01069 Dresden, Germany 3 Heliatek GmbH, Treidlerstraße 3, 01139 Dresden, Germany

bittrich-eva@ipfdd.de Recently, an outstanding power conversion efficiency of 12% was achieved for small molecule organic solar cells, comparable to that of inorganic thin film solar cells [1]. Small conjugated molecules (donor) are combined with C60 (acceptor) in the photoactive blend layer and the blend structure has to be optimized to ensure efficient exciton separation. For this purpose the film thickness should be only in the order of several 10 nm, in the range of the exciton diffusion length. Typically, a flat lying molecular orientation ensures maximum thin film absorption (at perpendicular illumination) in such thin films due to the parallel alignment of the molecule transition dipole moment [2]. Thus the challenge is to optimize the chemical structure of the organic molecules to achieve an optimum molecular orientation. We present joint results of experiments and theoretical simulations on pristine DCV4T-Et2 and blend DCV4T-Et2:C60 thin films [3]. The films were prepared by physical vapour deposition and the morphology characterized by variable angle spectroscopic ellipsometry, grazing incidence X-ray diffraction and atomic force microscopy. Molecular orientation, anisotropic optical constants, crystallinity and phase separation can be retrieved from the experimental data. Full-atomistic molecular dynamic simulation was used to characterize the impact of intermolecular and donor-substrate interactions on the molecular orientation of DCV4T-Et2 thin films.

[1] Heliatek 2013, www.heliatek.com/ (accessed February 12, 2013). [2] Schünemann, C.; Wynands, D.; Eichhorn, K.-J.; et al. J. Phys. Chem. C 2013, 117, 11600. [3] Guskova, O.; Schünemann C.; Eichhorn, K.-J.; et al. J. Phys. Chem. C 2013, 117, 17285.

Anisotropic optical constants of DCV4T-Et2 pristine film modeled from VASE data (left), sketch of the molecular orientation of the small organic molecules in the thin film (right) [3].

P63 REGRESSION SUM DECOMPOSITION OF MUELLER MATRICES FROM DEPOLARIZING BIOLOGICAL CHIRAL REFLECTORS Roger Magnusson1, Razvigor Ossikovski2, Enric Garcia-Caurel2, Kenneth Järrendahl1, Hans Arwin1

1 Linköping University, Department of Physics, Chemistry and Biology, Laboratory of Applied Optics, SE-581 83 Linköping, Sweden

2 CNRS, LPICM, Ecole Polytechnique, 91128 Palaiseau, France rogma@ifm.liu.se Many species of scarab beetles have exoskeletons, so called cuticles, with complex nanostructures. Michelson found already more than 100 years ago, that the reflected light from some beetles is near-circular polarized. Later this was attributed to chitin-based chiral multilayered structures in the outer part of the cuticles. We have used Mueller matrix ellipsometry for characterization of such structures and here we present data from green-colored Cetonia aurata which exhibits a metallic shine and also narrow-band, left-handed circular polarization features for green light in reflection. For blue and red light its cuticle appears like a dielectric mirror. The circular polarization effects are largest for normal incidence and vanish at grazing incidence. These nanostructures can be modeled with a twisted layered structure but a distribution in pitch is necessary to include to account for depolarization. The objective is here to show that the observed depolarizing Mueller matrices can be sum decomposed by regression into two non-depolarizing Mueller matrices MM and MC, corresponding to an ideal mirror and an ideal circular polarizer, respectively. The motivation for using only two matrices is that the measured Mueller matrix M only has two non-zero eigenvalues and thus a Cloude decomposition will only have two non-zero terms. The decomposition is described by MD = αMM + (1-α)MC, where we assume α to be scalar. We use M from near-normal experiments and with α as adjustable parameter, the Frobenius norm ||M-MD|| is minimized for each λ in the spectral region 400-900 nm. The α(λ)-spectrum agrees well with the eigenvalue λ1 of M and the second eigenvalue λ2 = 1 - λ1. Advantages with a regression approach are its simplicity and stability compared to a Cloude decomposition based on analysis of eigenvalues and eigenvectors. For more complex structures, the regression can be extended by adding more matrices up to a total of four.

P64 ELECTRICAL AND OPTICAL PROPERTIES OF Ag FILMS GROWN BY ION BEAM SPUTTER DEPOSITION Carsten Bundesmann, R. Feder, H. Neumann Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig carsten.bundesmann@iom-leipzig.de Tailoring thin film properties is of increasing technological interest. Ion beam sputter deposition (IBSD) is a physical vapor deposition (PVD) technique for growing thin films with better properties than other PVD techniques, because the generation and acceleration of the ions, the sputtering and the deposition processes are locally separated. Thus, by changing ion beam or geometrical parameters, angular and energetic distributions of sputtered and scattered particles are changed [1, 2], which leads to systematic variations of thin film properties [3, 4]. Here we present the application of IBSD for tailoring the electrical and optical properties of Ag films, which were grown under systematic variation of ion beam properties (ion species, ion energy) and geometrical parameters (ion incidence angle, polar emission angle). The films are characterized concerning their electrical and optical properties by 4-point-probe measurements (4PPM) and spectroscopic ellipsometry (SE), respectively. 4PPM reveals a systematic relation between process parameters and electrical resistivity (see figure). For instance, Ag films grown by sputtering with Xe ions show a lower electrical resistivity than those films grown by sputtering with Ar ions. The electrical resistivity increases further with increasing ion energy, with increasing ion incidence angle, and increasing polar emission angle. SE data analysis using the Drude-model confirms these trends, even though the numbers are slightly higher. The systematic changes of film properties are correlated with a change of structural properties (grain sizes). The grain sizes are found to be correlated with the mean scattering time extracted from the SE analysis.

[1] R. Feder et al., Nucl. Instrum. Methods Phys. Res., Sect. B, in press. [2] R. Feder et al., Nucl. Instrum. Methods Phys. Res., Sect. B, 316, 198-204 (2013). [3] C. Bundesmann et al., Thin Solid Films 516, 8604-8608 (2008). [4] C. Bundesmann et al., Thin Solid Films, in submission.

Electrical resistivity of Ag films grown under systematic variation of the polar emission angle. The results are shown for three sample sets grown by sputtering with Ar with varying ion incidence angle (0°, 30°, 60°) at a fixed ion energy of 1000 eV.

P65 TEMPERATURE-CONTROLLED CHARACTERIZATION OF VARIOUS MATERIALS BY SPECTROSCOPIC ELLIPSOMETRY Christophe Licitra1, Y. Doudaine1, L. Vignoud1, F. Piegas Luce1, F. Mazen1, J. Tillier2, E. Beche1, P. Noé1

1 CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 GRENOBLE Cedex 9, France. 2 CEA, LITEN, 17 rue des Martyrs, 38054 GRENOBLE Cedex 9, France.

christophe.licitra@cea.fr Various materials show an interesting shift of their properties with temperature allowing their integration in active devices such as phase-change memories, smart solar absorbers or reflectors, smart windows or laser protections. On the contrary, some materials show a detrimental loss of their properties when exposed to high temperatures. The characterization of such variations is important for materials integration. It is generally done at room temperature by measuring pre-annealed samples but it requires a lot of sample preparation and it generally does not detect sharp transitions. In addition some materials present reversible properties when cooled back to their initial temperature. Temperature-controlled ellipsometry can therefore be a useful technique to characterize the change of properties along with temperature as it allows the fast detection of phase transitions, refractive index and thickness variations, etc. In this study we will detail the use of temperature-controlled ellipsometry for the characterization of various materials. Depending on the application ultraviolet to near infrared or mid-infrared ellipsometry was used. This work was performed using an Instec heat cell (room temperature to 600° C) with two Woollam ellipsometers: M2000 in the ultraviolet to near infrared region and IR-VASE in the mid-infrared region. Applications are ranging from amorphous silicon layers on silicon to measure their solid phase epitaxial regrowth rate (see Fig.), vanadium oxide to measure the effect of the Mott transition on the optical properties from 0.19 nm to 10 µm, porous SiCOH materials to observe their degradation at high temperatures, chalcogenides to detect the amorphous to crystalline phase change and finally polymers used for 3D integration to measure their glass transition.

Thickness evolution of an amorphous silicon film on a silicon substrate during annealing at 600° C.

P66 GAS SENSORS USING THE SPR-EFFECT DETECTED BY ELLIPSOMETRY Daniel Fischer1, A. Nooke1, A. Hertwig1, M. Weise1, U. Beck1, M. Kormunda2

1 BAM Federal Institute for Materials Research and Testing, Division 6.7, Unter den Eichen 44-46, 12203 Berlin, Germany

2 J. E. Purkyne University, Faculty of Science, Department of Physics, Ceske mladeze 8, 400 96 Usti nad Labem, Czech Republic

daniel.fischer@bam.de During the industrial development of the last decades, improvements in process control have become more and more important. Due to the shortage of resources and the need for ecologically compatibility, one important aspect is the control of the gas flow in chemical facilities which is controlled by gas sensors. In the presented research, a new type of non-invasive gas sensors based on the SPR-effect with ellipsometric readout is demonstrated. In the past, the detection of flammable (hydrocarbons, H2), toxic (CO), oxidising (O2, O3) as well as inert (He, N2) gases was realized. Using a Kretschmann setup with gold as the sensing layer (40 nm) results in sensitivities in the range of 0.1% to 1% (in air) depending on the gas. However, unmodified gold as sensing layers are not useful for operation in ambient atmosphere over a long time because they are slowly covered by sulfides making the layer useless for gas sensing. To protect the layer, the gold surface was covered with a thin coating of a metal oxide. Additionally, we found a dramatically increased sensitivity (10 to 200 ppm) for the studied gases. Attempts to get better control of the adsorption process by using doped metal oxides are described. For iron-doped tinoxide (Fe:SnO2), a much better sensitivity (0.5 ppm CO in air, see figure) as well as a selectivity for this specific gas was found which is related to the high affinity of Fe(II)-ions to CO molecules. This effect could be a possible approach to build new gas sensors by using a specific coating for each gas type. To understand the microscopic processes enabling the enhanced gas sensing, additional layers have to be characterized in their optical properties very well. The best method for evaluation is spectroscopic ellipsometry (SE) where one can extract several optical constants and get a deeper understanding of the determined results. Further methods like AFM and XPS are used to identify the structure of the surface.

Gas sensing measurement for different CO quantities in synthetic air by using a Fe:SnO2 top-coated gold surface.

P67 NEW APPLICATIONS OF SPECTROSCOPIC IMAGING ELLIPSOMETRY IN THE FIELD OF ORGANIC PHOTOVOLTAIC (OPV) MATERIALS Christian Röling1, 2, Peter H. Thiesen1, Levent Toppare3, 4, 5

1 Accurion GmbH, Stresemannstr. 30, 37079 Göttingen, Germany 2 Georg-August-University Göttingen, Institute for Physical Chemistry, Tammannstraße 6, D-

37077 Göttingen, Germany 3 Middle East Technical University, Department of Chemistry, 06531 Ankara, Turkey 4 Middle East Technical University, Department of Biotechnology, 06531 Ankara, Turkey 5 Middle East Technical University, Department of Polymer Science and Technology, 06531

Ankara, Turkey pt@accurion.com For years the development of organic semiconductor materials as active layer for organic solar cells has become one of the main challenges in chemistry and applied physics. π-conjugated polymers are one of most efficient exponent regarding optical and electronic materials for organic solar cells. The π-conjugated polymers stand out due to their structural diversity and optoelectronic properties. The modification of the donor-acceptor-donor (DAD) architecture is a simple and efficient way to construct a well-defined π-conjugated system with low oxidation potential, broad absorption spectrum and low band-gap [1]. Controlling the morphology, homogeneity and the optical properties of the organic solar cell material is essential for optimizing the efficiency of organic solar cells when employing π-conjugated polymers as photoactive layer. Here we present the optical properties of two DAD type π-conjugated polymer films (PHEHT and DBQHT), produced on indium tin oxide doped glass slide (ITO) by Stille coupling [1]. The thin films were measured by using a spectroscopic imaging ellipsometer (Accurion, nanofilm_ep4, λ = 380 900 nm) with 10x objective, at an angle of incidence (AOI) of 50° and purposing a beam cutter to avoid backside reflections. The mean value of the thickness and the optical properties of selected regions of interests (Figure 1) were obtained by a fitting process using EP4-Model, Accurion. The optical properties shows bathochromic shift in the π-π* transition for PHEHT with rigid acceptor core.

[1] A. Durmus, G. E. Gunbas, P. Camurlu, L. Toppare, Chem. Commun., (2007) 3246-3248. [2] S. Tarkuc, Y. A. Udum, L. Toppare, Thin Solid Films, 520, (2012) 2960-2965.

Left – comparison of the ellipsometric high contrast image (grey) (Accurion, nanofilm_ep4) of a thin film of PHEHT on ITO/glass and a classical microscope image, including the region of interests (ROI). Right – comparison of the modelled n+k values of thin π-conjugated polymer film on ITO/glass (PDBQHT (red line) and PHEHT (blue line)) using two Lorentz and a Drude term.

P68 OPTICAL CHARACTERIZATION OF POLYMERIC THIN FILMS FOR PHOTOVOLTAIC APPLICATIONS BY ELLIPSOMETRY Veronika Schmiedova, P. Heinrichova, O. Zmeskal, M. Weiter Brno University of Technology, Faculty of Chemistry, Materials Research Centre, Purkynova 118, 612 00 Brno, Czech Republic xcschmiedova@fch.vutbr.cz Optical properties of π-conjugated polymers attract considerable attention due to their potential optoelectronic applications such organic photovoltaics (OPVs), organic light emitting devices (OLEDs) and others. The performance of polymeric OPVs are based on concept of bulk heterojunction created by nanostructured interpenetrating network of π-conjugated polymers acting as electron donors and electron acceptors, primarily fullerenes. The morphology of the resulting thin layer at nanoscale level and their optical and electrical properties are key parameters affecting the efficiency of OPVs. Thus the complex understanding of optical properties of photovoltaic thin films with respect to the thin layer morphology and polymers molecular structure are of primarily importance of organic photovoltaic research. In particular, the aim of this work is to characterize and model the complex refractive index and extinction coefficient spectra of thin nanostructured layers of four different photovoltaic polymers. Thin layers of MDMO-PPV (poly[2-methoxy-5-(3ˈ,7ˈ-dimethyloctyloxy)-1,4-phenylenevinylene]), PCDTBT (poly[1ˈ-di-2-thienyl-2ˈ,1ˈ,3ˈ-benzothiadiazole)]), PCBTDPP (poly[1-dioctyl-2,5-dihydropyrrolo[3,4-]pyrrole-1,4-dione]), PC60BM ([6,6]-phenyl-C61-butyric acid methyl ester), PC70BM ([6,6]-phenyl-C71-butyric acid methyl ester) and their mixtures were prepared by spin-coating on quartz glass. Optical properties were investigated by spectroscopy ellipsometry in the wavelength range of 200-850 nm and the Tauc Lorentz model was used for this matter. Thickness of the layers were measured by mechanical profilometer and used as an input parameter for optical modeling. Thin layers of MDMO-PPV, PC60BM and their blends were used as the reference samples, the results were compared with those already published. Based on the developed model, the ellipsometric data were analyzed with respect to the molecular structure of studied polymers and morphology of thin film layers.

P69 REAL TIME MONITORING OF ALD Adrian Blümich, H. Gargouri, G. Dittmar, U. Richter, B. Gruska SENTECH Instruments GmbH, Schwarzschildstraße 2, 12489 Berlin, Germany adrian.bluemich@sentech.de The controlled deposition of ultrathin films is of fundamental importance for further developments of the nanotechnology. 3D conformal deposition and control of film growth and material properties on the atomic level make atomic layer deposition (ALD) the most appropriate thin film technology. The specific properties of ALD (e.g. range of deposition temperature, operation pressure, growth rate, self-limiting surface reactions) recommend in situ monitoring of the process. The benefits are:

- Analyzing of film properties (growth rate, thickness, refractive index) during the ALD process - Analyzing films and stacks without breaking the vacuum - Developing new processes faster and more effective - Reducing the material consumption

Ellipsometry offers all advantages listed above. Hence, this measurement method is especially suited for in situ monitoring of ALD processes. While the spectral development of films is especially interesting for strongly absorbing materials like metals, single wavelength ellipsometry is suited to investigate film growth of transparent materials with high time resolution and precision. Spectroscopic ellipsometry in a range of 320 – 850 nm wavelength was applied to monitor the ALD deposition of Al2O3, SiO2, and ZnO films on Si. The measurements were performed, after every precursor pulse during enlarged purging periods. Thereby a linear growth rate was found for all deposited materials. Applying ellipsometry during the enlarged purging periods the adsorption and desorption due to the deposition of the precursor material and the subsequent purging could be shown. A change in the refractive index during the initial state of the deposition of SiO2 was observed by comparing simulated and measured (Ψ, Δ) single wavelength trajectories. Laser ellipsometry with higher light intensity and fast rotating analyzer is capable to monitor ALD processes with unmodified purging periods (fast cycle times). This is demonstrated for thermal ALD of Al2O3.

P70 ELLIPSOMETRIC ANALYSIS OF GRAPHENE LAYERS FROM DUV TO MIR Sven Peters, B. Gruska SENTECH Instruments GmbH, Schwarzschildstraße 2, 12489 Berlin, Germany sven.peters@sentech.de Spectroscopic ellipsometry is an ideal tool to measure thickness and optical constants of very thin absorbing films. For that, single and multilayer graphene are excellent examples [1]. Unfortunately, there are several challenges for the measurement of such films: (a) strong absorption and film thickness are correlated resulting in ambiguous number of graphene layers, (b) the film uniformity in research is often not high enough to assume only one configuration, (c) the influence of substrate nature is relative high. The exact knowledge of substrate preparation and film uniformity are prerequisite for a correct measurement of the optical constants of the single graphene film. Further, the application of the dispersion relation for single layer graphene can’t be applied to multiple layer graphene. Multiple angle spectroscopic ellipsometric measurements in the range from 190 nm to 25,000 nm were used together with high spatial resolution laser ellipsometry and reflectometry to analyse single and multiple layer graphene films on different substrates like SiC and silicon oxide on silicon. Laser ellipsometry and reflectometry were applied depending on the properties of the substrate. The dispersion of n and k were measured within the uniform sample areas using spectroscopic ellipsometry. Thereby, different oscillator models and combinations of them were used to describe n and k. Despite all these efforts no unique solution for the number of graphene layers of a particular film was found. The fit quality was often the same for different numbers of graphene layers. The reason is the strong correlation between thickness and absorption of the films. Using samples with well-known numbers of graphene layers allows us to measure the optical dispersion for those films. Different optical constants were found for different numbers of layers.

[1] F. J. Nelson, V. K. Kamineni, T. Zhang, E. S. Comfort, J. U. Lee, A. C. Diebold, Appl. Phys. Lett., 97, 253110 (2010).

P71 CHARACTERISATION OF RUTILE TiO2 LAYERS FOR HIGH PRECISION OPTICAL APPLICATION Thomas Modes, Waldemar Schönberger Fraunhofer Institute for Electron Beam and Plasma Technology FEP Winterbergstr. 28 01277 Dresden, Germany Thomas.Modes@fep.fraunhofer.de Titanium dioxide in the rutile modification is the material with the highest refractive index and transparent in visible wavelength range. The application of such a high refractive material would be desirable for high precision optical layer systems. Further requirements for these applications are homogenous layers with low roughness. Sputtering technology allows depositing amorphous TiO2 layers with high precision and high productivity on large scale. But these amorphous layers have a lower refractive index than the crystalline TiO2 layers. When depositing crystalline TiO2 layers at elevated substrate temperatures and by increased ion bombardment the layer growth often starts with lower refractive sub layer and the surface roughness is higher due to crystallites. For the optimisation of the process parameters a precise method is required to detect these features. With spectral photometry this is not always possible. By using spectroscopic ellipsometry with a 3-layer model, consisting of sublayer, top layer and surface roughness, a reliable characterisation is possible. The refractive index of the top layers was determined between 2.55 and 2.72. These high values could be assigned to rutile or rutile-anatase mixtures and was confirmed by X-ray diffraction. With spectroscopy ellipsometry the sublayers could be reliably characterised, even if there is only a small difference in the optical properties of sub and top layer. Using these results the process conditions could be optimised to reduce the difference in refractive index between sub and top layer from 0.3 to below 0.01. Furthermore, the modelling of roughness by ellipsometry could be approved by further roughness investigations like SEM or AFM and correlated well with haze measurements. It could be shown, that the spectroscopic ellipsometry allows the fast and reliable characterisation of sputtered rutile TiO2 layers in respect to optical properties influenced by microstructure gradients and surface roughness.

P72 OPTICAL AND NUCLEAR STUDIES OF MOS STRUCTURES Witold Rzodkiewicz1, M. Kulik2, J. Zuk2, A. Panas1, A. P. Kobzev3

1 Institute of Electron Technology, Al. Lotników 32/46, 02-668 Warszawa, Poland 2 Institute of Physics UMCS, Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin, Poland 3 The Frank Laboratory of Neutron Physics JINR, Joliot-Curie str., Dubna , Russia, 141980

rzodki@ite.waw.pl The characteristic dome-like shape distribution of electric parameters has been observed in our studies. Taking the results of our works into account, the following hypothesis was drawn: uneven shape distribution of electrical parameters have been arisen from the uneven shape of stress distribution under the metal gate. To prove or deny the assumed hypothesis, a lot of investigations on stresses in MOS structures are being performed. In our studies wafers with MOS (metal-oxide-semiconductor) structures annealed in different times were used. Spectroscopic ellipsometry was applied for determination of optical coefficients and thicknesses of metal and dielectric layers. Raman spectroscopy was used for stress determination in dielectric layer under the metal gate of MOS structures. The results of stress distribution in dielectric layer (SiO2) measured by Raman Spectroscopy in the vicinity of the metal gate (Al, AlSiCu) and under the gate were presented. At the edges of the gate and under the gate, tensile and compressive stresses were observed, respectively. In order to assure that is not caused by a composition change, the study of composition is needed. The study of the composition of electronic components constitutes the starting point of their characterization. Therefore, in this paper, we present experimental results of hydrogen, oxygen, aluminum, silicon, and copper concentrations in MOS structures carried out by the Rutherford backscattering spectrometry and elastic recoil detection methods. These techniques allow inter alia determination of silicon and oxygen content as a function of the position x on a wafer. On the basis of depth profile elastic recoil detection measurements performed on Al and AlSiCu gates, a much larger hydrogen content in the surface layer for MOS structure with Al gate was confirmed. Copper atoms were detected only in the AlSiCu gate.

P73 INTERFERENCE COLORS OF TiO2/Ti/GLASS SYSTEMS DEPOSITED BY MAGNETRON SPUTTERING Łukasz Skowroński1, M. Trzcinski1, A. Antończak3, M. Kustra1, P. Domanowski2, W. Wachowiak1, D. Bratz1, M. K. Naparty1, T. Hiller1, A. Bukaluk1, A. A. Wronkowska1

1 University of Technology and Life Sciences, Institute of Mathematics and Physics, Kaliskiego 7, 85-789 Bydgoszcz, Poland

2 University of Technology and Life Sciences, Faculty of Mechanical Engineering, Kaliskiego 7, 85-789 Bydgoszcz, Poland

3 Wroclaw University of Technology, Department of Electronics, Laser and Electronic Fiber Group, Wyb. Wyspiańskiego 27, 50-370 Wroclaw, Poland

lukasz.skowronski@utp.edu.pl Titanium and titanium oxides are used in many applications (e.g. implant material in bio-medicine, electrochromic devices, dye-sensitive solar cells, photocatalysis and others) [1]. Moreover, due to expressive colors of TiO2 deposited on metal, titanium dioxide can be applied as a decorative material architecture, automotive industry and jewelry [2, 3]. Titanium and titanium oxide films were deposited on float glass by means of large-sized magnetron sputtering. The technological parameters of sputtering (speed of substrate under the target, number of cycles of deposition, ratio of Ar and O2 flow) were varied to obtain different colors of the coatings. Thickness of the Ti undercoat determines the transparency of prepared films. The spectroscopic ellipsometry (SE) combined with transmittance (T) measurements were applied to evaluate the complex dielectric function (<ε(E)> = <ε1(E)> + i<ε2(E)> = <n>2) and thickness of Ti and TiO2 layers. The ellipsometric parameters were measured in the photon energy 0.06-6.0 eV for three angles of incidence (65°, 70° and 75°) using two instruments: V-VASE (J. A. Woollam Co., Inc.) and Sendira (SENTECH GmbH). The transmittance measurements were performed using V-VASE device in the UV-Vis-NIR spectral range and FTIR spectrophotometer Cary 640 (Agilent) in MIR region. The thickness of titanium opaque films was determined using the confocal optical microscope (COM) Lext OLS 4000 (Olympus). The surface topography of Ti and TiO2 films was examined by atomic force microscopy (AFM) Innova (Bruker). The XPS measurements were performed in a UHV chamber with a base pressure ≤2*10-10 mBar using Al Kα radiation (hν = 1486.6 eV) and hemispherical analyzer. In addition, we performed the colorimetric analysis of the obtained coatings.

[1] U. Diebold, Surf. Sci. Rep., 48(2003)53-229. [2] A. J. Antończak, et al., Appl. Phys. A, DOI 10.1007/s00339-013-7932-8(2013). [3] M.V. Diamanti, et al., Color Res. Appl., 33(2008)221-228.

Index of refraction <n> and extinction coefficient <k> of the dielectric function of titanium and titanium dioxide films.

P74 IN-SITU MONITORING OF ELECTRICAL PROPERTIES OF ULTRATHIN SILVER FILMS BY MEANS OF SPECTRAL ELLIPSOMETRY Jiri Bulir, Michal Novotny, Jan Lancok, Ján Tomko, Ladislav Fekete Academy of Sciences of the Czech Republic, Institute of Physics, Na Slovance 2, 182 21 Prague 8, Czech Republic bulir@fzu.cz Spectral ellipsometry exhibits a powerful tool for characterization of optical properties of bulk material and thin film. This method is very sensitive even to ultrathin films with thickness of few nanometers. We exploited this feature for monitoring of growth of silver layer allowing unambiguous classification of its growth mode: either Volmer-Weber (nanoislands formation) or Stranski-Krastanov (continuous layer growth). Silver exhibits a great potential for a fabrication of metal-dielectric transparent conductive coating due to its unique optical constants and excellent electrical properties. In this work, we deal with preparation of ultrathin continuous silver layer. The silver layers were deposited by RF magnetron sputtering. Typically, the growth of Ag layer is governed by Volmer-Weber mechanism, which is characterized by the isolated islands formation at the initial stage of the silver nucleation on a substrate. Nevertheless, we demonstrate that the nucleation process can be controlled by the deposition condition, plasma parameters and seeding layer. Thus an ultra-thin, continuous and smooth silver layer can be prepared using this method. The prepared ultra-thin continuous layers were thermally annealed. Both the deposition process and the thermal annealing were monitored by means of the spectral ellipsometry. The optical constants were analyzed using suitable model for evaluation of electrical resistivity of the prepared coatings. The surface morphology was analyzed by atomic force microscopy.

P75 OPTICAL AND MICROSTRUCTURAL PROPERTIES OF TiO2 LAYERS DEPOSITED ON FLOAT GLASS BY MAGNETRON SPUTTERING Łukasz Skowroński1, M. Trzcinski1, M. Kustra1, P. Domanowski2, W. Wachowiak1, M. K. Naparty1, T. Hiller1, A. Bukaluk1, A. A. Wronkowska1

1 University of Technology and Life Sciences, Institute of Mathematics and Physics, Kaliskiego 7, 85-789 Bydgoszcz, Poland

2 University of Technology and Life Sciences, Faculty of Mechanical Engineering, Kaliskiego 7, 85-789 Bydgoszcz, Poland

lukasz.skowronski@utp.edu.pl In last decades titanium oxide layers are extensively developed because they are non-toxic, bio-compatible and chemically stable. TiO2 is used in high-tech applications including electrochromic devices and dye-sensitized solar cells [1]. In this research, titanium dioxide films were deposited on float glass by means of a large-sized magnetron sputtering with varied technological parameters: speed of substrate under the target, number of cycles of deposition and ratio of Ar and O2 flow. The optical properties (the complex dielectric function, <ε(E)> = <ε1(E)> + i<ε2(E)> and transmittance spectra) and the effective thickness of the obtained layers have been determined using spectroscopic ellipsometry (SE) combined with transmittance measurements in the photon energy range from 0.06 eV to 6.0 eV. The ellipsometric parameters were measured for three angles of incidence (65°, 70° and 75°) using two instruments: V-VASE (J. A. Woollam Co., Inc.) and Sendira (SENTECH GmbH). The transmittance measurements were performed using V-VASE device in the UV-vis-NIR spectral range and FTIR spectrophotometer Cary 640 from Agilent in MIR. The surface topography of TiO2 films was examined by atomic force microscopy (AFM) Innova from Bruker. The XPS measurements were performed in a UHV chamber with a base pressure ≤2*10-10 mBar using Al Kα radiation (hν = 1486.6 eV) and hemispherical analyzer. Compositional depth profiles were taken using Ar+ ions of 4 keV energy and incidence angle 69°. Our investigation is focused on the influence of technological parameters of sputtering on optical and microstructural properties of the fabricated films.

[1] U. Diebold, The surface science of titanium dioxide, Surface Science Reports, 48 (2003) 53-229.

Real part <ε1> and imaginary part <ε2> of the dielectric function of titanium dioxide film. The inset is the AFM image of surface of TiO2 layer.

P76

YMnO3-BASED PHOTOCAPACITIVE DETECTORS IN THE VISIBLE LIGHT REGIME Om Shandilya Choudhary1, A. Bogusz1, L. Selvaraj1, V. John1, D. Bürger1, I. Skorupa1, A. Lawerenz2, K. Ettrich2, O .G. Schmidt1 ,3, H. Schmidt1

1 Chemnitz University of Technology, Faculty of Electrical Engineering and Information Technology, 09107 Chemnitz, Germany

2 CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH, 99099 Erfurt, Germany 3 Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Institute for Integrative

Nanosciences, 01069 Dresden, Germany om-shandilya.choudhary@s2011.tu-chemnitz.de YMnO3 is one of the few materials that exhibit ferroelectricity and antiferromagnetism. Ferroelectricity and antiferromagnetism in case of YMnO3 can be observed up to 900 K and 80 K, respectively. The remanent polarization of YMnO3 amounts to 2 µC/cm2 and metal- YMnO3-metal thin film structures can be switched between a high resistance state (HRS) and a low resistance state (LRS). In case of YMnO3 thin film, the transition from HRS to LRS (set process) occurs at the voltages 10 V and higher, while the transition from LRS to HRS (reset process) is triggered at the smaller voltages. This unipolar resistive switching is nonvolatile and has a resistance ratio of 5 orders of magnitude [1]. In pure YMnO3, absorption occurs throughout the entire visible light region, resulting in its black color [2]. This work investigates the effect of light-irradiation on the capacitance of YMnO3-based metal-ferroelectric-insulator-semiconductor (MFIS) structures (inset 1 in figure). The thickness and optical constants of all layers of the MFIS diodes have been investigated using spectral ellipsometry measurements with a VASE ellipsometer assuming the refraction index of SiN to be 1.95 [3]. The DC bias for the capacitance measurements was swept from +10 to -20 V and back under different light-irradiation at a sweep rate of ca. 130 mV/s. It has been found that under dark conditions two nonvolatile capacitance minima exists at -11 and at -3 V, possibly when the YMnO3 is in the LRS and HRS state, respectively (see figure). If we rewrite the +10 and -20 V branch in shorter period of time then, low capacitance state (LCS) is non-volatile and pseudo-volatile, respectively. Under illumination the capacitance at the two minima increases in the visible spectral range, depending on the wavelength illumination, YMnO3 thickness and YMnO3 capacitance state.

[1] A. Bogusz et al.: Resistive switching in thin multiferroic films, Proc. IEEE (2013), in press [2] A.E. Smith et al.: J. Am. Chem. Soc. 131, 17084 (2009) [3] A. Laades et al.: Phys. Stat. Sol. C 9, 2124 (2012)

Experimental CV characteristics of Al/ YMnO3/SiN/p-Si/Au diodes at 10 kHz and different wavelengths of light. Dotted and solid lines are obtained by sweeping DC voltage from +10 to -20 V and -20 to +10 V respectively. Inset 1: Schematic diode structure. Inset 2: Retention measurement of the capacitance in (HCS) and (LCS) at the two capacitance minima -3 (red) and -11 V (green) under dark conditions.

P77 OPTICAL PROPERTIES OF GRAPHENE DETERMINED BY SPECTROSCOPIC ELLIPSOMETRY, REFLECTOMETRY AND TRANSMISSION PHOTOMETRY Claus Villringer1, J. Bauer1, H. Lux1, S. Schrader1, F. De Matteis2, M. Casalboni2, O. Fursenko3, G. Lippert3, G. Lupina3, J. Kitzmann3

1 University of Applied Sciences Wildau, Bahnhofstrasse, 15745 Wildau, Germany 2 University of Rome 'Tor Vergata', Department of Physics, Via della Ricerca Scientifica 1,

001333 Rome, Italy 3 IHP Innovations for High Performance Microelectronics, Im Technologiepark 25, 15236

Frankfurt (Oder), Germany claus.villringer@th-wildau.de In this work, we present the determination of optical constants and thickness of graphene and few-layer graphene (FLG) by using variable angle spectroscopic ellipsometry, reflectometry and transmission photometry in the wavelength range from UV to NIR (0.2 µm - 3.3 µm). A modified filtered vacuum arc physical vapor deposition process and a chemical vapor deposition (CVD) process were used for deposition of large-area polycrystalline graphene and FLG directly on quartz substrate and on a silicon wafer coated with 300 nm silicon dioxide. Additionally, exfoliated graphene grown on copper by a CVD process was investigated. The dispersions of the complex refractive index were obtained by point-by-point fit of all measured data. The optical model was supported by Raman spectroscopy and atomic force microscopy measurements. A critical point oscillator model with Lorenz excitonic extension was used to parameterize the optical constants in the UV and visible spectral range, while a Drude model was applied at the NIR spectral range. Finally, comparison of the dispersions of optical constants and Raman measurements for graphene samples obtained by different technological processes was performed.

P78 A FAST LINE-ELLIPSOMETER Ferdinand Bammer1, B. Ullmann1, D. Hönig2, P. Collins3, T. Kehoe3

1 Vienna University of Technology 2 Accurion GmbH, Stresemanstr. 30, D-37079 Goettingen, Germany 3 IRIS Research and Development, Av. Carl Friedrich Gauss, 11. 08860 Castelldefels, Spain

f.bammer@tuwien.ac.at Printed electronics, e.g. organic photo-voltaic (OPV), is usually produced by roll-to-roll-printing. Thickness control is necessary to avoid deficient production and ellipsometry is one possibility for this. Most ellipsometers are too slow and/or measure only a spot. We developed a new concept, enabling fast measurement on a line, to acquire after a printing step 2D-information about the thickness-distribution. The light source, currently a 905 nm-laser-diode, is projected on a line across the 300 mm wide web. The reflected light is imaged on a line-sensor. The ψ/Δ-acquisition uses stroboscopic illumination. The laser-diode-light is polarized at 45°. Then the light enters the key-element, a single-crystal photo-elastic-modulator (SCPEM), an electrically excited LiTaO3-crystal oscillating at ~100 kHz and thereby modulating its birefringence. The laser diode is operated in pulsed mode with four different phases related to the modulator. For each phase an image with 10-100 pulses is taken. With the four images, ψ/Δ can be calculated. Depending on the number of pulses necessary for one image the sampling frequency can go up to 1 kHz. A prototype is currently being installed on a test rig. With stabilized operation of laserdiode and SCPEM, pixel-averaging, and thorough calibration sufficient sensitivity may be achieved for the quality-control of the active layer in OPV-production. This research has received funding from the European Union’s 7th Framework Programme (FP7/2007-2013) under Grant Agreement number 315665

P79 ELLIPSOMETRIC INFRARED MICROSCOPY Karsten Hinrichs1, A. Furchner1, J. Rappich2, K.-J. Eichhorn3, T. W. H. Oates1

1 Leibniz - Institut für Analytische Wissenschaften - ISAS - e.V., 12489 Berlin, Germany 2 Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut für Silizium-

Photovoltaik, Berlin, Germany 3 Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany

karsten.hinrichs@isas.de Optical constants and properties of anisotropic thin films such as electronic conductivity or molecular orientations are of high technological interest for design of efficient optical, electronic, and sensing devices. Standard Fourier Transform Infrared (FTIR) microscopy is used for mapping of polarization dependent optical properties of thin oxide and polymer films. The extension for ellipsometric microscopy is outlined. Optical properties of thin silicon oxide and indium tin oxide (ITO) films are measured and quantitatively characterized by optical calculations with respect to anisotropy, conductivity and thickness. For an about 1800 nm thick polyimide film, VIS ellipsometric mapping is compared with the IR microscopic mapping results. Keywords: Infrared Ellipsometry, Microscopy, Anisotropy, Thin films

[1] Karsten Hinrichs, Andreas Furchner, Jörg Rappich, Thomas W. H. Oates, J. Phys. Chem. C, 2013, 117 (26), pp 13557–13563

P80 TELLIPSOMETRY IN TWENTE: DYNAMICS OF THIN FILM MEMBRANES UNDER APPLIED TEMPERATURE PROFILES Emiel J. Kappert1, Wojciech Ogieglo2, Michiel Raaijmakers1, Beata Koziara2, Herbert Wormeester3, Nieck E. Benes1

1 University of Twente, Faculty of Science and Technology and MESA+ Institute of Nanotechnology, Inorganic Membrane, P.O. Box 217, 7500 AE Enschede, The Netherlands

2 University of Twente, Faculty of Science and Technology and MESA+ Institute of Nanotechnology, Membrane Science and Technology, P.O. Box 217, 7500 AE Enschede, The Netherlands

3 University of Twente, Faculty of Science and Technology and MESA+ Institute of Nanotechnology, Physics of Interfaces and Nanomaterials group, P.O. Box 217, 7500 AE Enschede, The Netherlands

n.e.benes@utwente.nl We use in-situ ellipsometry to study the structural and chemical evolution of thin films as function of the temperature (‘Tellipsometry’). Particular focus is on organic, inorganic, and hybrid materials that are relevant to artificial membrane fabrication and operation. Our poster shows some illustrative examples. Inorganic and hybrid materials The fabrication of thin inorganic and organic-inorganic hybrid thin films typically involves a temperature treatment step that dictates many of the final chemical and structural properties of the film. We present the changes density and thickness of sol-gel derived amorphous silica and organosilica films (~0.1 mu thick) upon heating to 550° C. For silica films, the shrinkage of the material closely follows the weight loss as recorded via thermogravimetric analysis. The densification behavior of organosilica layers is quite different. Where weight loss is recorded in thermogravimetric analysis, no shrinkage occurs in the thin film, implying a strong decrease in the density of the material upon heating. Organic materials It is well-recognized that the glass transition temperature of a polymer can be influenced by the presence of small penetrant molecules that dilate the material, thereby allowing increased macromolecular mobility. This is referred to as plasticization and is manifested by a reduction in the Tg. We quantify the depression of the transition temperature of thin films exposed to a solvent by in-situ ellipsometry, from the shift in the kink of a dilation-temperature curve. For example, for polystyrene exposed to n-octane the glass transition temperature drops from 100.0° C to 29.6° C. Thermal exposure may also cause changes materials chemistry. As example, we show the irreversible changes in UV light absorption of a sulfonated poly-ether-ether-ketone film heated to 220° C, due to desulfonation of the material.

P81 TIME-RESOLVED ELLIPSOMETRIC CHARACTERIZATION OF (Fe/Si)N MULTILAYER FILM SYNTHESIS Ivan Anatol'evich Tarasov1, S. N. Varnakov1, I. A. Yakovlev1, S. M. Zharkov1, 2, N. N. Kosyrev1, S. G. Ovchinnikov1, 2

1 Kirensky Insitute of Physics, 660036 Krasnoyarsk, Akademgorodok 50, Russia 2 Siberian Federal University, 660041 Krasnoyarsk, pr. Svobodniy 79, Russia

tia@iph.krasn.ru The (Fe/Si)n multilayer system is one of the most promising candidates for practical application due to its possibility of the spin polarized current injection from the ferromagnetic to the semiconducting layer. In addition, the interlayer exchange coupling between two the ferromagnetic layers across a nonmagnetic spacer along with the giant magnetoresistence makes this system applicable in mass storage and nonvolatile memory. The physical properties of this system are strongly dependent on the film thickness and the constitution of the interlayer spacer. The presence of nonmagnetic silicide phases in the interlayer is able to impair its useful properties. It is, thereby, important to control its composition since the silicides formation can both occur during and after the synthesis procedure. It has been shown it is highly influenced by the crystalline quality of the multilayers and particularly, by the interface roughness [1]. In this work we concentrate on the consideration of the interlayer boundary organization during the synthesis of (Fe/Si)n structures with n = 1, 2, 3 on Si(100) or Si(111) and the influence of the bottom layer constitution on the formation of the top ones by means of the synthesis monitoring by in-situ single-wave ellipsometry [2] and subsequent transmission electron microscopy investigations. Consequently, the dependence of the changes of the optical and structural properties on the evaporation time has been revealed.

[1] S. N. Varnakov, S. V. Komogortsev et al., J. Appl. Phys. 104, 094703 (2008) [2] I. A. Tarasov, N. N. Kosyrev et al., Technical Physics 57, 09 (2012)

P82 OPTICAL DIMENSIONAL CHARACTERIZATION OF DISORDERED SILICON NANOWIRE ARRAYS FOR PV APPLICATIONS Johannes Endres1, Martin Foldyna2, Gaoliang Dai1, Soumyadeep Misra2, Pere Roca i Cabarrocas2, Alexander Diener1, Bernd Bodermann1

1 Physikalisch-Technische Bundesanstalt Braunschweig, Germany 2 CNRS, LPICM Ecole Polytechnique, Palaiseau cedex, France

johannes.endres@ptb.de Radial P-I-N Junction Solar Cells are a very promising approach for stable and high performance thin film photovoltaics due to improved both optical and electronic properties. However, the performance of silicon nanowire arrays for PV applications is strongly dependent on geometric-dimensional parameters of the Si nanowires like size distributions, aspect ratio, wire density and orientation. High resolution microscopy methods like Atomic Force or Scanning Electron Microscopy (AFM, SEM) are commonly used to investigate these parameters. However, these methods are relatively slow and may be limited in some cases e. g. real 3D measurements of high density and high aspect ratio arrays. Classical optical methods like spectroscopic reflectometry or ellipsometry, on the other hand, are well suited for fast characterisation of optical features of these arrays, but do not offer access to the required dimensional parameters. To combine advantages of optical methods with local structure parameter sensitivity we investigate the potential and performance of focused beam scatterometry in the DUV spectral range. For this purpose we measured disordered silicon nanowire arrays for PV applications using PTB's high resolution goniometric DUV scatterometer. Using a spot diameter of about 40 µm and an illumination wavelength of 266 nm, we have achieved a high sensitivity and reproducibility of individual speckles, enabling access to local structure parameters. The measurements show a qualitatively good agreement with rigorously modelled scattered light intensity patterns based on AFM measurements.

Top left: Top down AFM image step mode Top right: Radial P-I-N junction structure Bottom: Scatterogram at 266 nm, different colours: repeated measurements show highly reproducible speckle patterns

P83 SPEEDING-UP IMAGING ELLIPSOMETRY DATA CUBES PROCESSING: A MULTIVARIATE APPROACH C. Guyot1, D. Hönig2, P. Thiesen2, Michel Voué1

1 Université de Mons, Physique des Matériaux et Optique, 20 Place du Parc, B-7000 Mons (Belgium)

2 Accurion GmbH, Stresemanstr. 30, D-37079 Goettingen, Germany michel.voue@umons.ac.be For 10 years, imaging ellipsometry (IE) has become a cornerstone analytical technique to obtain local information on the optical properties of heterogeneous and/or micro-structured surfaces. The drawback of the technique is obviously the increase of the data number and subsequently the time required to process them. Going from single wavelength IE (SWIE) to spectroscopic IE (SIE) contributes to the accuracy of the measurements and also to their flexibility. Nevertheless, it tremendously increases the complexity of the ellipsometric data inversion: two stacks of images have to be processed and reading corresponding pixels in each images leads to obtaining conventional local PSI and DELTA spectra. Moreover, the optical model may abruptly change from one pixel to the other, in terms of layer thickness but also in terms of materials. Finding an appropriate starting guess for the optimization procedure of the optical model reveals therefore to be almost impossible for complex samples. In the contribution, we propose a preprocessing of the data based on statistical classification methods of the pixels values. Using a combination of k-means algorithms and hierarchical clustering coupled to back-propagation of the results, we have shown that the processing time can easily be reduced from several hours to less the 5 min for SWIE data stacks. Examples will also be given for the spectroscopic case. Acknowledgements: CG and MV are financially supported by the National Fund for Scientific Research of Belgium (FRFC project n°1926111).

IE data acquired with Accurion EP3 imager for a 50 µm square pattern of SiO2 (thickness: 100 nm) on a native oxide (silicon substrate) (A: DELTA image; B: PSI image; C: final thickness image for the SiO2 structure.)

P84 SPECIFIC MODIFICATIONS TO ENHANCE SENSITIVITY IN NULL-ELLIPSOMETRY Marco Muth1, 2, R. P. Schmid1, K. Schnitzlein2

1 Brandenburg University of Technology Cottbus–Senftenberg, Institute of Physics and Chemistry

2 Brandenburg University of Technology Cottbus–Senftenberg, Chair of Chemical Reaction Engineering

marco.muth@tu-cottbus.de As film thickness decreases toward zero or increases toward the cycle thickness, ever-greater resolution and accuracy in the measurement of ψ is required in order to simultaneously determine both thickness and refractive index. The film thicknesses at which the ψ measurement is not longer sufficiently accurate depends on the film refractive index contrast and the particular ellipsometer used. We demonstrate an optimization, which enhances the accuracy of the critical ψ-value. It can be obtained, by shifting the azimuth angle of the compensator in PCSA null ellipsometry from the typical value of C = ±45°, to smaller angles. For a given layer structure, an optimum value for C can be calculated, which offers a magnified setting range of the analyzer azimuth A, and hence a more accurate determination of ψ, without losing the necessary accuracy in Δ. In addition sufficiently fast convergence is achieved. The proposed method is especially beneficial, when measuring very thin films with low refractive index contrast. A possible source of error in null ellipsometry could be low sensitivity to azimuth variations close to the null (since the intensity curve has a flat minimum), which makes finding the real null settings difficult or impossible. We demonstrate that the tuned compensator azimuth leads, in addition, to a refinement of the null setting process, by optimizing the curve progressions for both, polarizer and analyzer. A further improvement is demonstrated by the combination of a tuned compensator azimuth together with an optimized variable phase-retarder. Simulations and experimental results from different layer structures (e.g. enzyme layers on fluid interfaces) are shown to demonstrate the enhancement of the sensitivity.

P85 REAL-TIME SPECTROSCOPIC OFF-NULL ELLIPSOMETRY N. Reineking1, Dirk Hönig2

1 Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin 2 Accurion GmbH, Stresemannstr. 30, D-37079 Göttingen, Germany

dh@accurion.com Ellipsometry is a powerful tool for thin-film-characterization, but often it’s not suitable for real-time applications like process control. Here, we present a setup that allows the acquisition of about 1000 spectroscopic spectra per second with a thickness-sensitivity of less than 0.5 nm. This becomes possible by comparing the sample with a similar reference sample. Due to the orientation of the reference (see figure) it acts as an ideal compensator for all wavelengths. Hence no compensator is required. If the sample is equal to the reference, the outgoing light is linear polarized and can extinguished with a crossed analyzer. If there’s any difference between sample and reference, the light becomes elliptic polarized and the detected light flux increases. In order to maximize the rate of data acquisition, the analyzer is set to an off-null-position. During the measurement neither the polarizer- nor the analyzer-angle are changed, so the measurement speed is only limited by the intensity of the light source and the processing speed of the spectrometer.

The linear polarized white light is reflected from the reference at an angle of incidence of 20°. The sample is rotated by 90° referring to the beam axis. Therefore the p- and s-polarized part interchanges relating to the reference. If the sample is identical to the reference, the outgoing light is linear polarized.

P86 SPECTROSCOPIC IMAGING ELLIPSOMETRY IN UV RANGE Stefan Schneider, Dirk Hönig Accurion GmbH, Stresemannstr. 30, 37079 Göttingen, Germany dh@accurion.com Imaging Ellipsometry (IE) was introduced fifteen years ago and since then has been established as a powerful tool for the characterization of thin films. It combines the ability to derive optical parameters such as layer thickness or refractive index with high-contrast, high-resolution imaging. The fusion of imaging techniques and ellipsometry helps researchers worldwide to provide a deeper insight into their samples. Especially structured samples featuring very thin layers of material or coatings are regularly investigated in materials science, life science or quality control applications. The number of absorption phenomena like band – to band transition that can be characterized in thin films was increased with the introduction of UV-ellipsometry. The chance of getting this additional information for tiny samples is very promising. Due to the unique lateral resolution of imaging ellipsometry also parameter maps will be available. A high number of substrates are nontransparent in the UV, simplifying the thickness calculations to single layer problems. The determination of thickness maps on transparent substrates will benefit from this simplification. When it comes to instrumentation, extending into UV range imposes very strict and extensive limitations with regard to available components such as imaging optics, polarizing optics and detectors feasible for SIE. We will explain the technical challenges and special requirements of a UV-capable imaging ellipsometer and we will present some of the solutions to overcome existing issues. A focus will be put on a purpose-built, high performance microscope objective enabling high resolution imaging starting at a wavelength of 250 nm. Furthermore, for the first time, measurement results obtained with an UV-SIE will be presented and an outlook at current and future applications will be given.

Preliminary design of microscope objective “NC2”

P87 ADVANCED DUAL ROTATING-COMPENSATOR MUELLER MATRIX POLARIMETER IN TRANSMISSION CONFIGUR- ATION FOR CHARACTERIZATION OF POLARIZATION ELEMENTS IN THE VISIBLE SPECTRAL RANGE Josef Kapitan, Vadim Evseev Palacky University, Faculty of Science, Department of Optics, address: Tr. 17. listopadu 12, 77146 Olomouc, Czech Republic vadim.evseev@upol.cz The work on the development of a dual rotating-compensator Mueller matrix spectro-polarimeter in transmission configuration is presented. The polarimeter is developed for the characterization of various polarization elements used in the instrumentation for polarized Raman spectroscopy developed at the place of authors’ affiliation. The polarimeter configuration is based on the one from Ref. [1]. A general algorithm for processing the measurements including error compensation and calculation of Mueller matrices from measured modulated intensities, which takes into account variations in the configuration and operation parameters of the polarimeter, is presented in comparison with a published algorithm [2]. The calibration issues are addressed and the performance of the polarimeter is discussed. Currently, the polarimeter is optimized to perform the measurements in the 530-610 nm range with a step of about 0.1 nm. The accuracy is better than 0.01 on the elements of a normalized Mueller matrix. The polarimeter was used to measure the Mueller matrices, with their subsequent polar decomposition and retrieval of retardance [3], of a number of waveplates. The accuracy on the retardance obtained for the same waveplate but at the different azimuthal positions of its fast axis was observed to be better than 0.5%.

[1] Dennis H. Goldstein, Mueller matrix dual-rotating retarder polarimeter, Applied Optics, Vol. 31, No. 31, 1992

[2] Dennis H. Goldstein and Russell A. Chipman, Error analysis of a Mueller matrix polarimeter, J. Opt. Soc. Am. A, Vol. 7, No. 4, 1990

[3] Shih-Yau Lu and Russell A. Chipman, Interpretation of Mueller matrices based on polar decomposition, J. Opt. Soc. Am. A, Vol. 13, No. 5, 1996