crystal growth of iii/v semiconductor nanowires kobi greenberg
TRANSCRIPT
Crystal Growth of III/V Semiconductor Nanowires
Kobi Greenberg
Metal organic molecular beam epitaxy (MOMBE)
Future applications of nanowires
Martensson et al
Nanowire LED
Maarten et al
Single photon emitter
Algra et al
Crystal structure engineering
Nanowires as a Biological Interface
Mårtensson et al
The vapor liquid solid growth mechanism
TMI
420oC
In
P2Au catalyst
InP
TEM pictures of InP nanowires grown in our lab by the vapor liquid solid method
ZB
WZ
Au
InP
Two ways to arrange cannon ballsCubic structureHexagonal structure
Stacking fault formation
A
B
C
A
B
C
A
B
A
B
A
B
Zincblende nanowire Wurzite nanowireWurzite nanowire
With stacking fault
A
B
C
B
A
B
SF
Limitations of the vapor liquid solid method
• Difficult to eliminate stacking fault • Very sensitive to wafer surface effects
Calahorra, Greenberg et al. nanotechnology 2012
TMI 420oC
In
P2Au catalyst
InP
The selective area vapor liquid solid growth method
Si3N4
Dalacu et al, Nanotechnology 2009
Au catalyst
TMI
420oC
P2
TEM pictures of InP nanowires grown in our lab by selective area vapor liquid solid method: no stacking faults
Advantages of the selective area vapor liquid solid method
• Easy to eliminate stacking fault in InP nanowires
• not sensitive to wafer surface effects
• Predictable growth rate
Si3N4
Au catalyst
TMI420oC
P2
Fabrication
Wafer cleaning
Si3N4 deposition
Electron sensitive resist coating
Electron beam lithography + development+ BOE
InP<111>B substrate
Gold evaporation
Lift off
nanowire heterostuctures: important for device applications
• conventional layers of materials having different lattice constant cannot be grown on top of each other as single crystals.
• Due to their small dimensions, a stack of materials with different lattice constants can be grown as a single crystal
GaP
InGaP
Heterostructure analysis by EDX and STEM HAADF
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2
3
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2
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Summary
• Selective area vapor liquid solid is the method of choice for defect free nanowire growth.
• Heterostructures of InP and GaP having 7.7% lattice mismatch were demonstrated.
• Method will be implemented for other materials such as GaAs, GaP,InAs and their heterostuctures.