The rate-limiting step in the thermal oxidation of silicon carbide

Using first-principles density-functional calculations of the total energy, we performed a systematic study of the diffusion activation energies of O2 and CO in SiO2 and Si1−xCxO2. Our results suggest that the dense Si1−xCxO2 (e.g., Si2CO6) layer may play a critical role in the SiC thermal oxidation process. The out-diffusion of CO through SiO2 or Si2CO6 is the controlling step of the SiC thermal oxidation. Known experimental data are explained well by our results.