Structure and energetics of carbon defects in SiC (0001)/SiO2 systems at realistic temperatures: Defects in SiC, SiO2, and at their interface

We report first-principles calculations that reveal the atomic forms, stability, and energy levels of carbon-related defects in SiC (0001)/SiO₂ systems. We clarify the stable position (SiC side, SiO₂ side, or just at the SiC/SiO₂ interface) of defects depending on the oxidation environment. Under an O-rich condition, the di-carbon antisite ((C₂)Si) in the SiC side is stable and critical for n-channel MOSFETs, whereas the di-carbon defect (Si-C-C-Si) at the interface becomes critical under an O-poor condition. Our results suggest that the oxidation of SiC under a high-temperature O-poor condition is favorable in reducing the defects, in consistent with recent experimental reports.