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

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 N-2 molecules when the areal density of N atoms is larger than 3 x 10(14) 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 x 10(15) (1 x 10(15)) 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 N-2 desorption are important for understandings of the atom-scale mechanism of N-incorporation behavior at 4H-SiC/SiO2 interfaces.