Atomic-Scale Dynamics of the Formation and Dissolution of Carbon Clusters in ${\mathrm{SiO}}_2$

Oxidation of SiC produces ${\mathrm{SiO}}_2$ while CO is released. A “reoxidation” step at lower temperatures is, however, necessary to produce high-quality ${\mathrm{SiO}}_2$. This step is believed to cleanse the oxide of residual C without further oxidation of the SiC substrate. We report first-principles calculations that describe the nucleation and growth of O-deficient C clusters in ${\mathrm{SiO}}_2$ under oxidation conditions, fed by the production of CO at the advancing interface, and their gradual dissolution by the supply of O under reoxidation conditions. We predict that both CO and ${\mathrm{CO}}_2$ are released during both steps.