Ab Initio Molecular Dynamics Approach for Oxidation of SiC Surface in Contact with Aqueous H2O2 Solutions

Controlling the oxidation of silicon carbide (SiC) is a key factor in fabricating SiC-based devices, such as power-integrated circuits and thermal protection systems. Oxidation is particularly utilized for machining SiC in conjunction with chemical–mechanical polishing. However, a thorough understanding of SiC oxidation at the microscopic level is lacking. Here, we performed ab initio molecular dynamics simulations to elucidate the microscopic mechanisms of the oxidation of OH- and H-terminated SiC surfaces in contact with an oxidizing solution─aqueous H₂O₂ solution. We found that the OH-terminated (0001) C-face surface of SiC is more easily oxidized than the OH-terminated (0001) Si-face and H-terminated C- and Si-faces. The stability of the C–O and Si–O species on the surface plays a key role in the oxidation of the OH-terminated surfaces. The effect of H₂O₂ concentration on the oxidation of the C-face was also examined. We found that the OH radicals generated from H₂O₂ molecules undergo a facile conversion to H₂O molecules in a pure H₂O₂ solution. This phenomenon may explain the counterintuitive dependence of oxidation on the H₂O₂ concentration observed in the experiments.