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Comparative morphology of AuTiAlTi, AuPdAlTi and AuAlTi ohmic contacts to AlGaN/GaN

Published online by Cambridge University Press:  11 February 2011

M W Fay
Affiliation:
School of Mechanical, Materials, Manufacturing Engineering and Management, University of Nottingham, University Park, Nottingham NG7 2RD, UK
G Moldovan
Affiliation:
School of Mechanical, Materials, Manufacturing Engineering and Management, University of Nottingham, University Park, Nottingham NG7 2RD, UK
I Harrison
Affiliation:
School of Electrical and Electronic Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK
R. S. Balmer
Affiliation:
QinetiQ Ltd, St Andrews Rd, Malvern, Worcs WR14 3PS, UK
K P Hilton
Affiliation:
QinetiQ Ltd, St Andrews Rd, Malvern, Worcs WR14 3PS, UK
B T Hughes
Affiliation:
QinetiQ Ltd, St Andrews Rd, Malvern, Worcs WR14 3PS, UK
M J Uren
Affiliation:
QinetiQ Ltd, St Andrews Rd, Malvern, Worcs WR14 3PS, UK
T Martin
Affiliation:
QinetiQ Ltd, St Andrews Rd, Malvern, Worcs WR14 3PS, UK
P D Brown
Affiliation:
School of Mechanical, Materials, Manufacturing Engineering and Management, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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Abstract

AuTiAlTi, AuPdAlTi and AuAlTi ohmic contacts to AlGaN/GaN layers rapid thermal annealed at temperatures up to 950°C have been characterised using conventional and chemical transmission electron microscopy techniques. The relationship between the as-deposited metallic structure, annealing temperature, post-anneal interfacial microstructure and contact resistance is examined.

The presence of a TiN interfacial layer is found to correlate with the onset of ohmic behaviour. Ti and Pd barrier layers are found to be ineffective at stopping the diffusion of Au to the interface. Au is implicated in the development of the inclusions, which are associated with threading dislocations. Once activated, the presence of the inclusions has little influence on the ohmic behaviour of the sample.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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