Ohmic contacts to p-type GaN using a Ni/Pt/Au metallization scheme

We report a new Ni/Pt/Au trilayer metallization scheme for the formation of ohmic contact to p-GaN. Metal thin films with a thickness of 20 nm for Ni, 30 nm for Pt, and 80 nm for Au were deposited on the p-GaN layer (N-a = 9. 4 x 10(16) cm(-3)) by electron beam evaporation. The samples, annealed at 5 00 degrees C for 30 s in a rapid thermal anneal system, showed a high quali ty ohmic contact with a low specific contact resistance of 2.1 x 10(-2) Ome ga cm(2). Auger electron spectroscopy analysis of the contact layers sugges ts that Pt plays an important role in the formation of ohmic contact, indic ating that a Ni/Pt/Au trilayer can be used and that it is a promising mater ial system for ohmic contact to p-GaN. (C) 1998 American Vacuum Society. [S 0734-211X(98)00606-4].