Surface oxidation of alpha-silicon carbide by O2 from 300 to 1373 K

Article abstract of DOI:10.1016/0039-6028(91)90167-Q

Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS) were used to investigate the oxidation of single crystal α-SiC over a wide temperature and O₂ pressure range. In ultra-high vacuum, the surface composition of α-SiC (0001ˉ) as a function of temperature changes due to oxide formation and the sublimation of SiO and Si, yielding graphitic surface carbon. From 300 to 833 K, exposure of Ar⁺ bombarded α-SiC to 10^-8 Torr O₂ results in a two-stage oxidation process which yields a submonolayer oxide. Highly disordered α-SiC surfaces were found to oxidize faster and more extensively than well-annealed, ordered surfaces. Exposure of the α-SiC{0001} surfaces to 1 atm O₂ resulted in the production of SiO₂ overlayers, which were examined using XPS and Scanning AES (SAES). In these experiments the (0001ˉ) surface produced thicker SiO₂ overlayers than the (0001) surface. However, the difference in oxide thickness between the two {0001} surface was not as dramatic as previously reported and varied from sample to sample. Carbon was not detected in the surface SiO₂ layers formed between 973 and 1373 K, which suggested carbon was removed as CO and/or CO₂ during the SiC oxidation process.