HIGH-TEMPERATURE BEHAVIOR OF PT AND PD ON GAN

We report on the thermal stability of Pt and Pd thin films on GaN up t o 800 degrees C. We have found that for Pt thin films submicron size m etal spheres form at temperatures as low as 600 degrees C and the film turns into discontinuous islands at 725 degrees C and above. Pd begin s to form islands above 700 degrees C and areas of the film begin to d elaminate due to thermally generated compressive stress. The general b ehavior of these films is that found for most metal films on ceramics, suggesting that metals on GaN do not react as they typically do on co mmon elemental and compound semiconductors. This ceramic-like behavior must be considered when determining which metals may act as good elec trical contacts for GaN, especially for high temperature applications or alloyed contacts. (C) 1997 American Institute of Physics.