Dependence of energy gaps and effective masses on atomic positions in hexagonal SiC

The fundamental band gap, the crystal field splitting, the spin-orbit splitting and the effective electron and hole masses in the hexagonal polytypes 2H, 4H, and 6H of SiC have been computed for various lattice constants and basis atom positions. Results indicate that the exact positions of the hexagonal planes have a strong impact on the crystal-field splitting. However, the hexagonal planes have no effect on the band gap, spin-orbit splitting and the effective electron and hole masses.