Surface and interface study of PdCr/SiC schottky diode gas senosr annealed At 425 deg C

摘要

The surface and interface properties of a Pd_(0.9)Cr_(0.3)Cr_(0.1)/SiC Schottky diode gas sensor both beore and after annealing are investigated using Auger electron spectroscopy (AES), scanning electron spectroscopy (SEM), and energy dispersive spectroscopy (EDS). At room temperature the alloy reacted with SiC and formed Pd_xSi only in a very narrow interfacial region. After annealing for 250 hours at 425 deg C, the surface of chottky contact area has much less silicon and carbon contaimation than that found on the surface of an annealed Pd/SiC structure. Pd_xSi formed at a broadened interface after annealing, but a singificant layer of alloy film is still free of silicon and carbon. The chromium concentration with respect to palladium is quite uniform down to deep interface region. A stable catalytic surface and a clean layer of Pd_(0.9)Cr_(0.1) film are likely responsible for significantly improved device sensitivity.