Ni/Pt ohmic contacts to p-GaN

摘要

Sputtered Ni/Pt contacts to p-GaN (p chemical bounds 4.6 x 10~(17) cm~(-3)) are reported and compared to sputtered Ni, Pt, and Ni/Au comtacts. Sequential rapid thermal annealing was employed with smaples receiving an initial five minute heat treatment of 400 deg C followed by one minute anneals at 500, 600, and 700 deg C , all under flowing N_2. Plots of current versus voltage for all contacts showed nonlinearity through the origin as deposited and for all annealing conditions. Extracted values of contact resistivity were determined by the circular transmission line method using the measured resistance at 10 mA. The lowest contact resistivity was reproducibly provided by the Ni/Pt contacts after a l minute anneal at 600 deg C. After the 600 deg C anneal, the contact resistivities were 0.015 OMEGA cm~2 and 0.018 OMEGA cm~2 for the Ni (100 A)/Pt (1000 A) and the Ni (500 A)/Pt (1000 A) contacts, respectively. All other metallizations yielded contact resistvities from 0.03-0.05 OMEGA cm~2. Possible reasons for the lower contact resistivity of the Ni/Pt contacts are discussed.