Diffusion of carbon oxides in SiO2 during SiC oxidation: A first-principles study

The diffusion mechanisms of CO and CO2 molecules in SiO2 during SiC oxidation are theoretically investigated by means of total-energy calculations within the density-functional theory. We find characteristic features of the stable structures of carbon oxides depending on polymorph of SiO2. The calculated formation energies and diffusion energy barriers of CO and CO2 in SiO2 also reveal that the CO2 can be a dominant species of product gas caused by SiC oxidation. On the basis of calculated results, we propose that the outward diffusion of carbon oxides as well as the reaction processes at SiO2/SiC interface is rate-limiting during SiC oxidation on the Si-face. (C) 2013 AIP Publishing LLC.