First-principles investigations for oxidation reaction processes at 4H-SiC/SiO2 interface and its orientation dependence

The reaction processes of O-2 molecule at 4H-SiC/SiO2 interface are investigated by performing electronic structure calculations within density functional theory. Our calculations demonstrate characteristic features of the reaction depending on the crystal orientation of SiC: The energy barriers of CO formation at the interface are much lower than those of C-C bond formation. This implies that the reaction forming CO molecules, expressed as SiC+(3/2)O-2 -> SiO2 + CO, preferentially occurs during the interfacial reaction processes of SiC oxidation. Furthermore, the energy barrier for CO formation on the (000 (1) over bar) C-face is found to be lower than that on the (0001) Si-face, indicating that the reaction on the C-face easily occurs compared with that on the Si-face. On the basis of calculated energy barriers, it is also suggested that the formation of CO molecule at SiO/SiO2 interface depending on the orientation could be rate-limiting during SIC oxidation. (C) 2015 Elsevier B.V. All rights reserved.