SILICON OXYCARBIDE FORMATION ON SIC SURFACES AND AT THE SIC SIO2 INTERFACE/

Amorphous and single-crystal alpha-SiC were exposed to various oxygen sources at room temperature. The oxygen sources included the residual gas in an ultrahigh vacuum environment, ambient air, ozone, and oxygen plasma. X-ray photoelectron spectroscopy (XPS) was used to follow cha nges in the surface composition and to determine the local bonding env ironment of the Si atoms. It was found that silicon oxycarbide species are formed when these SiC materials are initially exposed to oxygen. With extended exposure to ambient air, a SiO2 layer is subsequently fo rmed over the silicon oxycarbide. However, the native oxide on the sin gle-crystal SiC consists mainly of silicon oxycarbide species. The thi cknesses of these native oxides were calculated using the XPS data. (C ) 1997 American Vacuum Society.