Ab initio calculations for the effect of wet oxidation condition on the reaction mechanism at 4H–SiC/SiO2 interface

Abstract

The reaction of a O2 molecule coexisting with wet oxidants such as a H2O molecule and OH groups at the 4H–SiC/SiO2 interface is investigated by performing ab initio calculations. Our calculations demonstrate characteristic features of the reaction depending on the wet oxidation condition. We find several possible reactions of oxidants different from those of O2 and H2O molecules obtained by previous calculations. On the Si-face, a H2O molecule and single OH group hardly contribute to the reaction at the interface, which results in the formation of a CO molecule from the dissociation of the O2 molecule. In contrast, a CO2 molecule is formed in the SiO2 region after the reaction of both O2 and H2O molecules on the C-face. We also find that the reaction of O2 accompanied by a wet oxidant is more thermally activate than those by O2 and H2O molecules. These results suggest that the oxidation reactions can be promoted by controlling the wet ambient condition.