Ab initio study for orientation dependence of nitrogen incorporation at 4H-SiC/SiO2 interfaces

Abstract

The incorporation behavior of N atoms at the 4H-SiC/SiO2 interface is theoretically investigated on the basis of ab initio calculations. We find that the incorporation energy of N atoms at the Si-face interface is ranging from −1.87 to −1.12 eV, which is much higher than those at the C-face and m-face interfaces. Furthermore, the incorporation of O atoms of NO molecules at the Si-face interface leads to the desorption of N atoms as N2 molecules when the areal density of N atoms is larger than 3 × 1014 cm−2, while the incorporation of N atoms of NO molecules preferentially occurs on the C-face (m-face) interface until the areal density of N atoms is less than 2 × 1015 (1 × 1015) cm−2. The calculated results suggest that the difference in the reaction energies depending on the plane orientation and the competition between N-incorporation and N2 desorption are important for understandings of the atom-scale mechanism of N-incorporation behavior at 4H-SiC/SiO2 interfaces.