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Optimizing n+ Ohmic Contacts on GaAs for HemtS

Published online by Cambridge University Press:  25 February 2011

H. M. Harris  and
J. R. Farley
H. M. Harris
Affiliation:
Physical Sciences Laboratory, Georgia Tech Research Institute, Atlanta, Georgia 30332
J. R. Farley
Affiliation:
Physical Sciences Laboratory, Georgia Tech Research Institute, Atlanta, Georgia 30332
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Abstract

Low ohmic contact resistance is essential for high performance microwave and millimeter wave transistors. Rapid thermal processing (RTP) has been used to optimize the ohmic contact resistance of gold - germanium / nickel / gold metallizations on gallium arsenide (GaAs) layers for high electron mobility transistor (HEMT) applications. A HEMT layer structure consisting of a 9000Å buffer layer grown on a semi-insulating substrate followed by a 20Å undoped AlGaAs spacer layer, a 700Å Al0.22Ga0.78 As layer doped at 1.0 × 1018cm-3and a 500Å GaAs cap layer doped at 1.5 × 1018 cm°C to 450°C. Time at temperature was varied from 10 seconds to 1 minute. Optimum conditions for our equipment and layer structure were found to be 365°C for 30 seconds. These conditions produced contact resistances of 0.08 ohm-mm (approximately 2.0 times better than the standard furnace alloy process).

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 260: Symposium C – Advanced Metallization and Processing for Semiconductor Devices and Circuits , 1992 , 475
Copyright
Copyright © Materials Research Society 1992

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References

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