Improved Low Resistance Contacts of Ni/Au and Pd/Au to p-Type GaN Using a Cryogenic Treatment
This article was presented as part of Symposium W, "Gallium Nitride and Related Alloys" at the 1999 Fall Meeting of the Materials Research Society held in Boston, Massachusetts, November 28-December 3
Abstract
A low resistance Ohmic contact to p-type GaN is essential for reliable operation of
electronic and optoelectronic devices. Such contacts have been made using Ni/Au and
Pd / Au contacts to p-type Mg-doped GaN (1.41x1017 cm-3 ) grown by metalorganic
chemical vapor deposition ( MOCVD ) on ( 0001 ) sapphire substrates. Thermal
evaporation was used for the deposition of those metals followed by annealing at
temperatures of 400-700 °C in an oxygen and nitrogen mixed gas ambient, then
subsequently cooled in liquid nitrogen which reduced the specific contact resistance from
the range of 9.46-2.80x10-2
cm2to 9.84~2.65x10-4
cm2for Ni/Au and from the range
of 8.35-5.01x10-4
cm2to 3.34-1.80x10-4
cm2for Pd/Au. The electrical characteristics
for the contacts were examined by the current versus voltage curves and the specific
contact resistance was determined by use of the circular transmission line method (c-TLM).
The effects of the cryogenic process on improving Ohmic behavior (I-V linearity)
and reducing the specific contact resistance will be discussed from a microstructural
analysis which reveals the metallurgy of Ohmic contact formation.
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 5S1, W11.77 (2000).
last updated Wednesday, May 17, 2000 5:02:16 PM.
© 2000 The Materials Research Society