Ab initio calculations of some electronic and elastic properties for SiC polytypes

Some electronic properties and elastic constants of the 3C-, 4H- and 6H-SiC polytypes are calculated using ab initio simulation program ABINIT, based on the Density Functional Theory approach. The calculations are performed within the Local-Density Approximation, with pseudopotential parametrized by Troullier and Martins. The total energies per atom for the 3C, 4H and 6H structures are very close and moreover satisfy the condition E3C > E6H > E4H. Thus, the 4H-SiC structure appears to be more stable than the other ones 3C and 6H. The analysis of elastic properties also indicates that the 4H-SiC polytype is stiffer than the other two structures. Hence, the important properties of SiC may manifest certain dependence on the polytypism. Our results are in qualitative and quantitative agreement with the existing experimental and theoretical studies.