Competing atomic and molecular mechanisms of thermal oxidation-SiC versus Si

Oxidation is widely used to fabricate complex materials and structures, controlling the properties of both the oxide and its interfaces. It is commonly assumed that the majority diffusing species in the oxide is the dominant oxidant, as is for Si oxidation. It is not possible, however, to account for the experimental data of SiC oxidation using such an assumption. We report first-principles calculations of the pertinent atomic-scale processes, account for the observations, and demonstrate that, for Si-face SiC, interface bonding dictates that atomic oxygen, the minority diffusing species, is the dominant oxidant.