Temperature-driven crystalline ordering and ohmic contact formation of PdAu layers on p-type GaN

We have investigated the effect of thermal annealing on the electrical characteristics of Pd/Au contact layer to p-GaN and on its crystalline ordering. While an as-deposited Pd/Au layer on p-GaN showed Schottky-contact characteristics, a thermally annealed Pd/Au layer yielded Ohmic characteristics, accompanying single-crystalline ordering with an abrupt interface with GaN. The Ohmic contact characteristics and crystalline ordering of PdAu layer were attributed to the substantial elimination of oxidation layers at the interface during thermal annealing.