Oxygen stability, diffusion, and precipitation in SiC: Implications for thin-film oxidation
We report a set of first-principles calculations of oxygen stability, diffusion, and precipitation in cubic SiC. The calculations show that i) oxygen has a very low solubility in SiC which explains why it is not incorporated in large quantities during growth. ii) The atomic-scale mechanisms of the nucleation and growth of SiO2 precipitates in cubic SiC proceed via the formation of a three-oxygen cluster analogous to the well-known “thermal donor” in Si. Emission of a CO molecule converts it into SiO2-like precipitate that can grow further. We suggest that similar processes can account for the observed CO emission during SiC oxidation and the trapping of C atoms at the SiC-SiO2 interface. iii) The above mechanisms for SiO2 precipitation remain practically the same under different doping conditions. This suggests that no difference in SiC-SiO2 interfaces should be observed under n- or p-type substrate doping.