A theoretical study on the thermal oxidation of silicon carbide: Chemical species at the SiO$_{\mathrm{2}}$/SiC interface*

Silicon carbide (SiC) is potentially a suitable candidate of the channel materials of power devices since it has wide bandgap, high electron mobility, and thermal conductivity. Furthermore, it is favorable for device fabrication as it can be thermally oxidized to create insulating silicon oxide (SiO$_{\mathrm{2}})$ layer. However, the SiC devices of current technology do not show acceptable performance because of a defective nature of the created SiO$_{\mathrm{2}}$/SiC stacking structure, which causes problems such as channel mobility degradation, threshold voltage increase, and leakage current. The origins of the defective nature are not understood so far, though it is presumed that they are rather concentrated at the interface. In the present study, we have performed first principles calculations to know the chemical species possibly produced at the oxide interface of thermally oxidized SiC. The First principles simulation code PHASE/0 (\underline {http://www.ciss.iis.u-tokyo.ac.jp/riss/english/project/device/}) was used in the theoretical calculations.