PRIN 2004-2005

LECCE PISA TORINO

MODELS AND NOISE MEASUREMENTS IN NANOSTRUCTURES

PROJECT STRUCTURE OVERVIEW

Web site: www.cmtg.it

PROJECT: MODELS AND NOISE MEASUREMENTS IN

NANOSTRUCTURES

• Total budget: 220.900 € (MIUR funding: 150.000 €)

• Start date: 1st January 2004

• Duration: 24 months

• First half year meeting, Lecce, June 18th, 2004

• Coordinator contact details:

DII - University of Lecce – Prof. Lino ReggianiAdministrative in charge Miss Gabriella Panareo

Lecce team

- REGGIANI Lino Prof. Ordinario FIS/03- PENNETTA Cecilia Prof. Associato FIS/03 - ALFINITO Eleonora Ricercatore FIS03- ROSINI Marcello Assegnista - LEUZZI Maria Tec. Laureato El. Dati- COLA Adriano CNR Ricercatore senior - MONTAGNA Giovanni CNR Tecnico - STARIKOV Jevjenij Semiconductor Physics Institute

Vilnius Lithuania senior scientist - SHIKTOROV Pavel Semiconductor Physics Institute

Vilnius Lithuania senior scientist - REKLAITIS Antanas Semiconductor Physics Institute

Vilnius Lithuania leading scientist

Pisa Team

- MACUCCI Massimo : Prof. Ordinario ING-INF/01

- BASSO Giovanni : Ricercatore ING-INF/01

- PENNELLI Giovanni : Ricercatore ING-INF/01

Torino team:

- MAZZETTI Piero: Prof. Ordinario FIS/03

- CARBONE Anna Filomena: Ricercatore Universitario FIS/03

Project Management

Deliverable 1st year

Deliverable 2nd year

Evaluation tasks

Lecce first year deliverables

Milestone 3.1.1

Theoretical analysis of shot noise in single and a double barrier resonant diodes.

Determination of the spectral density of current fluctuations for different geometries and

different values of the temperature as a function of the applied electrical potential.

Milestone 3.1.2

Analysis of the Fano factor for the determination of the effects due to the electrostatic

nteraction and the Pauli principle.

Milestone 3.1.3

Investigation of the electronic noise in the presence of periodic fields of high intensity in

homostructures and Schottky diodes.

Milestone 3.1.4

Development of a stochastic model based on percolative techniques for the study of

excess noise in ultrathin films with intrisic defects on an atomic scale length.

Pisa first year deliverables

Milestone 1.1.1Development of a code for the simulation of transport and shot noise in mesoscopic structures, in the presence of randomly distributed dopants, with the inclusion of realistic confinement potentials.

Milestone 1.1.2Development of an ultra low noise measurement system operating at cryogenic temperature, using correlation techniques and the substitution impedance method. The system will be optimized from the point of view of its immunity to vibrations and interferences of external origin, assessing also the thermal stability that can be achieved keeping the sample a few millimeters over the surface of the cryogenic liquid.

Milestone 1.1.3Shot noise measurements on double-barrier resonant-tunneling devices, with specific emphasis on the low-current operating condition, that can be investigated for the first

time with the new measurement system.

Torino first year deliverable

Milestone 2.1.1

Development of a suitable statistical model accounting for the correlation between

consecutive electrons in order to determine the current noise power spectrum in the

general case of negative feedback of the electron transit through the device.

Optimization of the noise measurement set-up in order to perform measurements of

optical gain, noise gain and detectivity in extreme operative conditions of the devices. In

particular noise measurements will be performed at liquid helium temperature and in

presence of infrared radiation. The devices are supplied by Dr. H.C. Liu (NRC, Canada).

Milestone 2.1.2

Measurements of noise in Josephson junctions and thin superconducting flms,

characterized by a very low noise, whose power spectral density is of the order of 10^(-

20) V^2/Hz. The junctions can be irradiated by means of an optical fiber entering the

cryostat. This allows to detect the effects of the electromagnetic radiation on the I-V

characteristic and on the noise of the junction. Development of a theoretical model able

to explain the results.

Lecce second year deliverables

Milestone 3.2.1

Comparison of the obtained results for the shot-noise through Monte Carlo techniques with those obtained by the partners of the project and search for unifying microscopic interpretations.

Milestone 3.2.2

Investigation of the nongaussianity associated with excess noise of Lorenzian and 1/f type in a biased resistor network.

Milestone 3.2.3

Investigation of the noise in homojunctions and Schottky diodes underconditions of periodic fields with high amplitude and frequency (TeraHertz region).

Milestone 3.2.4

Comparative analysis of the theoretical approaches developed by this unity with those developed by partners and/or exixting in the literature. Comparison of the theory with the experimental results available from the literature and/or obtained within the project.

Pisa second year deliverables

Milestone 1.2.1

Development of simulation codes for the analysis of transport and noise in

nanostructures, in the presence of a magnetic field orthogonal to the fevice plane.

Optimization of such codes with the application of the gauge that is most

appropriate for the representation of the vector potential, on a case by case basis.

Milestone 1.2.2

Development of a correlation measurement system for the dilution refrigerator that

is currently being acquired by the group.

Milestone 1.2.3

Transport and shot noise measurements on multiple chaotic cavities and

on extended quantum wires characterized by partially or completely

diffusive transport.

Torino second year deliverables

Milestone 2.2.1

Calculation of the noise power spectrum in multi quantum well device on the basis

of the models.developed in the first year. Experimental evaluation of current noise

as a function of several operating parameters of the devices (applied voltage,

Optical power, photon energy) will be performed. Such measurements will be

exploited to obtain the main figures of merit of the devices and to validate the

above described model.

Milestone 2.2.2

Noise measurements on Josephson junctions and high Tc superconducting films,

down to a temperature of 30 millikelvin, using a cryostat recently developed in our

laboratory. The experimental results will be compared with the theoretical ones

expected from the noise generation model developed in the first year of activity.

EVALUATION TASKS

• At the end of the phase one (12 months) we will organize a worksop with the same title of the project where each unity will present a scientific seminar on the activity carried out. The workshop will be publicized at an european level to provide an interantional audience on the subject.

• The scientific responsible of each unity will jointly prepare a conclusive report within the time span of the project itself by collecting the publications resulted from the project, taking into account the impact factor of the journals, of the attendance at international and national conferences on the subject with oral and poster contributions, of the patents which might be obtained within the experimental tasks

• .This report will contain a global evaluation of the scientific results achieved within the project and will be made available on the WEB site of the participating Universities.

• Scheduled Conferences 2005

• Fluctuation and Noise - FaN (may, Texas University, USA)

• Unsolved Problems of Noise - UPoN (june, Gallipoli – Lecce, Italy)

• International Conference on Noise and Flutuations – ICNF (september, Salamanca, Spain)

Patner milestone time due status

Lecce 1 1st year pending

Lecce 2 1st year pending

Lecce 3 1st year pending

Lecce 4 1st year pending

Pisa 1 1st year pending

Pisa 2 1st year pending

Pisa 3 1st year pending

Torino 1 1st year pending

Torino 2 1st year pending

Patner milestone time due status

Lecce 1 2nd year pending Lecce 2 2nd year pendingLecce 3 2nd year pendingLecce 4 2nd year pendingPisa 1 2nd year pendingPisa 2 2nd year pendingPisa 3 2nd year pendingTorino 1 2nd year pendingTorino 2 2nd year pending

Workplan revisions and triggering of

contingency plans