High temperature Pd-SiC Schottky diode gas sensors are known to thermally degrade due to interdiffusion and reaction at the metal-semiconductor interface. To understand and possibly eliminate this problem, detailed surface studies of thermally induced Pd-SiC surface interactions have been performed. These experiments compare standard 6H-SiC (0001) surfaces typical of those used in device fabrication with periodically stepped surfaces prepared by high temperature hydrogen etching. The Pd films range in thickness from the monolayer level (∼0.4 nm) to actual device dimensions (∼46.5 nm) and are deposited under ultrahigh vacuum conditions at ∼50 °C. These films are characterized in-situ using Auger electron spectroscopy both before and after annealing at 670 °C. The Auger lineshapes provide quantitative information on the chemistry of the reaction products. Ex-situ atomic force microscopy is used to characterize changes in surface morphology.