Atomic-Scale Mechanisms of Oxygen Precipitation and Thin-Film Oxidation of SiC

We report first-principles calculations in terms of which we describe the atomic-scale mechanisms of the nucleation and growth of ${\mathrm{SiO}}_2$ precipitates in cubic SiC. A three-oxygen cluster is found to be analogous to the well-known “thermal donor” in Si. Emission of a CO molecule converts it into an ${\mathrm{SiO}}_2$-like precipitate that can grow further. We propose that similar processes can account for the observed CO emission during SiC oxidation and the trapping of C atoms at the $\mathrm{SiC}-{\mathrm{SiO}}_2$ interface.