Atomic-Scale Dynamics of the Formation and Dissolution of Carbon Clusters in SiO2

Oxidation of SiC produces SiO(2) while CO is released. A "reoxidation" step at lower temperatures is, however, necessary to produce high-quality 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 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 CO(2) are released during both steps.