Effects of Wet Ambient on Dry Oxidation Processes at 4H-SiC/SiO2 Interface: An Ab Initio Study

Abstract

The reaction processes of O2 molecule with wet oxidant such as H2O molecule at the interface between 4H-SiC and SiO2 are investigated by performing ab initio calculations. On the Si-face, the formation of CO molecule from O2 molecule occurs without the reaction of H2O molecules. The calculated energy barrier for the CO formation from O2 molecule agrees with that of single dry oxidation, indicating that H2O molecule hardly contributes to oxidation reaction process at the Si-face interface. In contrast, both O2 and H2O molecules are easily incorporated into the C-face interface, resulting in the CO2 formation. The energy barrier for the reaction is lower than those of single dry and wet oxidations. Therefore, the coexistence of O2 and H2O molecules promotes the oxide growth at the C-face interface. These calculated results suggest that the activation energies of interfacial reaction processes on the C-face SiC crucially depend on wet ambient condition.