Ab initio study of structural and electronic properties of planar defects in Si and SiC -: art. no. 195344

We present ab initio calculations for internal interfaces in Si and SiC. Density-functional calculations within the local-density approximation and the pseudopotential-plane-wave approach are performed to understand the effect of such two-dimensional defects on the electronic properties. We study the interface between the 3C and 2H polytypes along the [111]/[0001] direction. A {221} tilt boundary between two cubic crystals, which is often observed in chemical vapor deposited films of SiC, is examined. We also consider the interface corresponding to a {115}/{3 (3) over bar 02} plane between the 3C and 2H phases. It is especially interesting since it may contribute to a quantum-wirelike inclusion of cubic SiC in hexagonal SiC. Whereas the {111}/{0001} interface induces only shallow states in the bulk fundamental gaps, the particular bond-ring topology of the {221} and {115}/{3 (3) over bar 02} interfaces gives rise to a variety of states, even resulting in a metallic behavior in the latter case for SiC.