one dimensional metal nanowires grown by physical vapour
TRANSCRIPT
Max-Planck-Institut für Intelligente Systeme
One dimensional metal nanowire grown by
physical vapor deposition
DSL
D S LÜNN CHICHT ABOR
Gunther Richter
Max Planck Institute for Intelligent Systems
(formerly MPI for Metals Research)
Stuttgart, Germany
MECANO Meeting, Ecole des Mines, Paris
30th October 2012
Max-Planck-Institut für Intelligente Systeme
Acknowledgment
Universität Stuttgart/MPI für Intelligente Systeme
Karla Hillerich Lisa Hofacker Matthias Kolb Matthias Schamel
Carola Schopf Dominic Linsler Christian Kappel Vanessa Dörlich
Friderike Baras Dominic Zug
Horst P. Strunk
Karlsruher Institut für Technologie
Wenting Huang Andreas Sedlmeyr Reiner Mönig
Oliver Kraft
Max-Planck-Institut für Intelligente Systeme
Overview
Motivation
Examples in nature
Artificial metal nanowhisker:
- Microstructure
- Growth
Nucleation site
Incorporation site
- Mechanical properties
- Composites
Summary
Max-Planck-Institut für Intelligente Systeme
Influence of FIB machining?
Motivation
2 µm2 µm
FIB cutting top-down approach
PVD growth bottom-up process
2 µm
Andreas Schneider
for nano structuring
Max-Planck-Institut für Intelligente Systeme
Overview
Motivation
Examples in nature
Artificial metal nanowhisker:
- Microstructure
- Growth
Nucleation site
Incorporation site
- Mechanical properties
- Composites
Summary
Max-Planck-Institut für Intelligente Systeme
Historical Whisker: hair silver
Max-Planck-Institut für Intelligente Systeme
Whisker 1574
Found in:
Freiberg
Schwarzwald
Kupferberg
Joachimsthal
Kongsberg
AgS_Heizent.wmv
As long as I am talking about silver matte, I should for the sake of the eager reader tell something that is
characteristic of its nature and behaviour. First: When silver matte is cast into an ingot, and while it is still
hot, it can be hammered and shaped as you wish, just like lead. And further: It is possible to cats figures or
coin medals from it which look like vitreous silver.
When you have cast it into funny little decorative figures, lightly cut or scratch them with a knive and hold
them over a gentle charcoal fire until they get hot, whereupon silver will sprout or grow out of them very
delicately just as it grows in the mineral. This is amusing and very pretty to watch. I am telling this so that
anybody who would like to do this for fun and play with it some more should know how it is done.
Max-Planck-Institut für Intelligente Systeme
Old reviews
Max-Planck-Institut für Intelligente Systeme
Whisker 1574
Vorkommen:
Freiberg
Schwarzwald
Kupferberg
Joachimsthal
Kongsberg
Max-Planck-Institut für Intelligente Systeme
Whisker 1574
Vorkommen:
Freiberg
Schwarzwald
Kupferberg
Joachimsthal
Kongsberg
Max-Planck-Institut für Intelligente Systeme
Overview
Motivation
Examples in nature
Artificial metal nanowhisker:
- Microstructure
- Growth
Nucleation site
Incorporation site
- Mechanical properties
- Composites
Summary
Max-Planck-Institut für Intelligente Systeme
arteficial Whisker
Substrate: Silicon wafer, Tungsten foil + 30 nm Carbon by magnetron sputtering
Growth parameters: UHV (2·10-10 mbar), Metal thermal evaporation, TS ~ 60% TM
Cu growth: TS = 650°C – 700°C, R = 0.05 nm/s
Crystal morphology: needle / prismatic, diameter 20 -200 nm, Length < 300 µm
Isometric Copper islands grown on a clean Silicon surface
Max-Planck-Institut für Intelligente Systeme
Microstructure
No defects as grain boundaries or
dislocations
the metallic whisker are perfect
single crystalline [011] [111]
[101]
a
bc
x
yz
1.0 nm
ab
c
Copper
Max-Planck-Institut für Intelligente Systeme
Nano-whisker tip
x [111]
Max-Planck-Institut für Intelligente Systeme
HRTEM || whisker axis
10 nm
HRTEM investigation:
e-beam axis: - no edge dislocations detectable
- no screw dislocation detectable
- projected side facets flat
- surface oxidized
- no contaminations visible on surface
e-beam || axis: - 6-fold symmetry
- no stacking faults
- misfit dislocations in Ni
- no dislocations in Cu whisker
- Ni/Cu core-shell structure
- Ni grows epitaxial by island growth
Max-Planck-Institut für Intelligente Systeme
Crystal shape
Shape:
- Low indexed {111}, {100} facets for surface
- Low energy Wulff shape dominates geometry
Max-Planck-Institut für Intelligente Systeme
Fe Nanowhisker
Substrate: Mo foil
Temperature: 800°C α-Fe
Surface not defined by low surface energy {110} facet
[001]
[100]
[010]
Max-Planck-Institut für Intelligente Systeme
Overview
Motivation
Examples in nature
Artificial metal nanowhisker:
- Microstructure
- Growth
Nucleation site
Incorporation site
- Mechanical properties
- Composites
Summary
Max-Planck-Institut für Intelligente Systeme
Mathematical NW lengthening model
Ruth, V & Hirth, J.P., Kinetics of diffusion-controlled whisker growth, J. Chem. Phys. 41, 3139-3149 (1964)
Metal
flux 5 min 120 min 120 min
Max-Planck-Institut für Intelligente Systeme
Substrate surface contribution
0
1000
2000
3000
4000
5000
6000
7000
8000
0,0E+00 2,0E-04 4,0E-04 6,0E-04 8,0E-04 1,0E-03 1,2E-03 1,4E-03
Whisker length [m]
Tim
e [
s]
100200
300400
500600
0
2
4
6
8
10
12
14
5
10
15
20
Beta
Diff
usio
n le
ngth
(µm
)
Whisker radius (nm)
Vl (m/s) w/D (1/m2) ß X (µm)
4,4E-08 6,8E+06 10,6 380
1,3E-08 1,9E+07 57,2 230
2,2E-08 3,0E+07 0,5 180
2,0E-08 7,2E+06 9,2 370
1,8E-07 9,1E+08 0,7 33
Whisker growth:
- NW growth by adatom diffusion on
substrate surface
- direct impingement on whisker facets
- Adatom incorporation: tip or root
Whisker formation:
- nucleation at preferred sites
- transformation from 2D nucleus to 1D
proto-whisker
- predominant growth by adatom
diffusion on substrate surface
- direct impingement on whisker facets
- whisker formation kinetically driven
Max-Planck-Institut für Intelligente Systeme
Substrate-Whisker interface
Si substrate
CuxSi
Ni film
C layer
Ni/Cu whisker
Sabine Haag
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C-Film Structuring
Preferred nucleation in C holes
Max-Planck-Institut für Intelligente Systeme
Growth mechanism I
1800
1900
2000
2100
2200
2300
2400
0 10 20 30 40 50Beschichtungszeit t [min]
Länge [nm
]
Sequence of deposition steps:
30 nm C/Si(111)
10 min deposition @ 680°C
SEM analysis
Secondary nucleation on NW side
facets
island growth
No lengthening
deactivation of atom incorporation
Max-Planck-Institut für Intelligente Systeme
50 nm Au colloids deposited by spin coating
Artificial nucleation site
30 nm deposition steps @ 680°C
Lengthening and structure rotation
Incorporation site still active
Growth mechanism II
Max-Planck-Institut für Intelligente Systeme
Growth mechanism III
Fe-Cu-nanowhisker:
1. 180 nm Cu @ 680°C
2. 30 nm Fe @ 680°C
substrate 30 nm/Si(100)
Miscibility gap
TEM grid
Formation of second
phase (Fe rich) at
interface
Nucleation and film
growth on NW surface
Max-Planck-Institut für Intelligente Systeme
Phenomenological growth model
Suitable Substrate:
- Si
- metal surface
Nucleation site:
- Colloids
- Defects in “non-wetting layer”
Metal condensation
Adatom diffusion
Nucleation
Nuclei growth
“Proto-whisker formation”
Nucleation and layer growth
on facets
Thickening
Adatom incorporation at
interface
Lengthening
Max-Planck-Institut für Intelligente Systeme
Overview
Motivation
Examples in nature
Artificial metal nanowhisker:
- Microstructure
- Growth
Nucleation site
Incorporation site
- Mechanical properties
- Composites
Summary
Max-Planck-Institut für Intelligente Systeme
cyclic in situ bending
Max-Planck-Institut für Intelligente Systeme
0 50 100 150 200 250 3000
2
4
6
8
be
nd
ing
stre
ss (
GP
a)
diameter (nm)
-2 -1 0 1 2 3 4 50
1
2 graphisch bestimmt
berechnet
y-K
oo
rdin
ate
in
m
x-Koordinate in m
Results
0 50 100 150 200 250 3000
1
2
3
4 m=0.47
shea
r st
ress
(GPa
)
diameter (nm)
m=0.41
Mckenzie
Frenkel
Bending stress:
- Lower limit of strength by curvature measurement
- No diameter dependence
Only small dislocation free volumes are tested
(colmpare results from Bei and Pharr)
Shear stress
whisker axis || <110> calculation of shear stress
- Close to predicted value for partial dislocation
(compare talk R. Mönig)
Max-Planck-Institut für Intelligente Systeme
Overview
Motivation
Examples in nature
Artificial metal nanowhisker:
- Microstructure
- Growth
Nucleation site
Incorporation site
- Mechanical properties
- Composites
Summary
Max-Planck-Institut für Intelligente Systeme
Advanced microstructures: Au-Ag core shell
structures
0 1 2 3 4 5 6
Ag L
Inte
nsity
(a.u
.)
Energy (keV)
Au M
50 nm
10 µm 4 µm 2 µm
A
D E
B C
D E
Max-Planck-Institut für Intelligente Systeme
Au-Ag core shell structures: Annealing
10 µm 1 µm2 µm
A B C
D
Measurement area and
microscope type
IAu Mα/IAg Lα
as deposited
IAu Mα/IAg Lα
after annealing
Film SEM Ag not detectable 11.9
0.5
Whisker SEM 0.4
0.1 12.2
2.8
Whisker TEM 0.5
0.1 13.9
1.3
Max-Planck-Institut für Intelligente Systeme
Au(Ag)-Metallic nano-tubes
2 nm
[100]
[011]
200 nm
022
111
111
-
-
- -
[011]
Max-Planck-Institut für Intelligente Systeme
Tube formation: Model
A B C D
: Substrate and Au grain boundaries : Au: Ag
Ag nano-whisker growth:
- Si(100) substrate
- R = 0.05 nm/s, TS = 800°C
- Cooling to RT
Max-Planck-Institut für Intelligente Systeme
Tube formation: Model
A B C D
: Substrate and Au grain boundaries : Au: Ag
Au film deposition:
- TS = RT no interdiffusion
- R = 0.02 nm/s cube-on-cube epitaxy on Ag whisker
polycrystalline Au film on substrate, columnar grains
- grain diameter ~ 100 nm
Max-Planck-Institut für Intelligente Systeme
Tube formation: Model
A B C D
: Substrate and Au grain boundaries : Au: Ag
Au(Ag) nano-tube formation:
- TS < 300°C activation of Ag diffusion
- t = 70 h D = 2.7·10-25 m2/s L ~ Å
Dgb = 7.6·10-15 m2/s Lgb ~ µm
- Ag depletion by surface diffusion
H. Mehrer, Ed., Landolt-Börnstein New Series, Group III:
Crystal and Solid State Physics, Volume 26, Diffusion in Solid Metals and Alloys (Springer-Verlag Berlin 1990)
Max-Planck-Institut für Intelligente Systeme
Tube formation: Model
A B C D
: Substrate and Au grain boundaries : Au: Ag
Au(Ag) nano-tube:
- wall thickness < 10 nm, length ~ 15 µm
- single crystalline, dislocation free, stacking faults from wall formation
- attached to substrate
- no Kirkendall effect but lost-wax process
H. Mehrer, Ed., Landolt-Börnstein New Series, Group III:
Crystal and Solid State Physics, Volume 26, Diffusion in Solid Metals and Alloys (Springer-Verlag Berlin 1990)
Max-Planck-Institut für Intelligente Systeme
Non Metal Nanowhisker
• Electron beam deposition of NaCl @ 250°C
• Evaporation of Na-Cl dimers
• Substrate: MgO, Al2O3, Ge, W
• Growth direction: <100>
• 2nd material deposition (e.g. V)
Core shell structures without Kirkendall effect
Max-Planck-Institut für Intelligente Systeme
Summary
Nanowhiskers:
- Unique microstructure Wulff-shape
- Root growth Arrays of nanowhiskers by tuning nucleation site
- 3D-substrate Advanced composites
- Unique properties Theoretical mechanical strength limit reached
Max-Planck-Institut für Intelligente Systeme
Acknowledgment
Universität Stuttgart/MPI für Intelligente Systeme
Karla Hillerich Lisa Hofacker Matthias Kolb Matthias Schamel
Carola Schopf Dominic Linsler Christian Kappel Vanessa Dörlich
Friderike Baras Dominic Zug
Horst P. Strunk
Karlsruher Institut für Technologie
Wenting Huang Andreas Sedlmeyr Reiner Mönig
Oliver Kraft
Thank you for your attention!