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Ohmic Contact Formation to Doped GaN

Published online by Cambridge University Press:  21 February 2011

L. L. Smith ,
M. D. Bremser ,
E. P. Carlson ,
T. W. Weeks Jr. ,
Y. Huang ,
M. J. Kim ,
R.W. Carpenter  and
R. F. Davis
L. L. Smith
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907
M. D. Bremser
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907
E. P. Carlson
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907
T. W. Weeks Jr.
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907
Y. Huang
Affiliation:
Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704
M. J. Kim
Affiliation:
Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704
R.W. Carpenter
Affiliation:
Center for Solid State Science, Arizona State University, Tempe, AZ 85287-1704
R. F. Davis
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907
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Abstract

Ohmic contact strategies for n- and p-type GaN have been investigated electrically, chemically, and microstructurally using transmission line measurements, high-resolution EELS and cross-sectional TEM, respectively. The contributions to contact performance from work function differences, carrier concentrations, annealing treatments, and interface metallurgy have been examined. The contact materials of Ti, TiN, Au, and Au/Mg were deposited via electron beam evaporation; Al was deposited via thermal evaporation. As-deposited Al and TiN contacts to highly doped n-GaN were ohmic, with room-temperature specific contact resistivities of 8.6×10−5 Ω cm2 and 2.5×10−5 Ωcm2 respectively. The Ti contacts developed low-resistivity ohmic behavior as a result of annealing; TiN contacts also improved with further heat treatment. For p-GaN, Au became ohmic with annealing, while Au/Mg contacts were ohmic in the as-deposited condition. The performance, structure, and composition of different contact schemes varied widely from system to system. An integrated analysis of the results of this study is presented below and coupled with a discussion of the most appropriate contact systems for both n- and p-type GaN.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 395: Symposium AAA – Gallium Nitride and Related Materials: The First International Symp , 1995 , 861
Copyright
Copyright © Materials Research Society 1996

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References

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