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Investigation of Aluminum and Titanium/Aluminum Contacts to n-Type Gallium Nitride

Published online by Cambridge University Press:  10 February 2011

B. P. Luther ,
S. E. Mohney ,
T. N. Jackson ,
M. Asif Khan ,
Q. Chen  and
J. W. Yang
B. P. Luther
Affiliation:
Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802
S. E. Mohney
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, mohney@ems.psu.edu
T. N. Jackson
Affiliation:
Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802
M. Asif Khan
Affiliation:
APA Optics, Inc., 2950 N.E. 84th Lane, Blaine, MN 55449
Q. Chen
Affiliation:
APA Optics, Inc., 2950 N.E. 84th Lane, Blaine, MN 55449
J. W. Yang
Affiliation:
APA Optics, Inc., 2950 N.E. 84th Lane, Blaine, MN 55449
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Abstract

We report on a study of Al and Ti/Al contacts to n-type GaN. Al contacts on n-GaN (7 x l017cm-3) annealed in forming gas at 600°C reached a minimum contact resistivity of 8x10~6Qcm2 and had much better thermal stability than reported by previous researchers. Ti/Al (35nm/l 15nm) contacts on n-GaN (5xl0I7cm~3) had resistivities of 7 x l0"6Qcm2 and 5xl0"6Qcm2 after annealing in Ar at 400°C for 5min and 600°C for 15sec, respectively. Depth profiles of Ti/Al contacts annealed at 400°C showed that low contact resistance was only achieved after Al diffused to the GaN interface. We propose that the mechanism for ohmic contact formation in Ti/Al contacts annealed in the 400-600°C range includes reduction of the native oxide on GaN by Ti and formation of an Al-Ti intermetallic phase in intimate contact with the GaN. Contacts with different Ti/Al layer thicknesses were investigated and those with 50nm/100nm layers had the same low resistance and better stability than 25nm/125nm contacts.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 449: Symposium N – III-V Nitrides , 1996 , 1097
Copyright
Copyright © Materials Research Society 1997

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References

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