Electronic structure and the local electroneutrality level of SiC polytypes from quasiparticle calculations within the GW approximation

Abstract

The most important interband transitions and the local charge neutrality level (CNL) in silicon carbide polytypes 3C-SiC and nH-SiC (n = 2–8) are calculated using the GW approximation for the self energy of quasiparticles. The calculated values of band gap Eg for various polytypes fall in the range 2.38 eV (3C-SiC)-3.33 eV (2H-SiC) and are very close to the experimental data (2.42–3.33 eV). The quasiparticle corrections to Eg determined by DFT-LDA calculations (about 1.1 eV) are almost independent of the crystal structure of a polytype. The positions of CNL in various polytypes are found to be almost the same, and the change in CNL correlates weakly with the change in Eg, which increases with the hexagonality of SiC. The calculated value of CNL varies from 1.74 eV in polytype 3C-SiC to 1.81 eV in 4H-SiC.