Density-functional theory study on electronic structure and optical property of 6H-SiC

To study electronic structures and optical properties of 6H-SiC, the lattice parameter, band structure, density of state, electron density difference and optical property of 6H-SiC are investigated by applying the first-principles density functional theory based on the plane wave pseudo-potential method in this paper. The results show that 6H-SiC is an indirect band gap semiconductor, and the valence band top is located at Γ, the conduction band bottom is located at (0, 0·50, 0·06) of M-L. The valence-band top is primarily from the hybrid of 2p states of C and Si atoms, while the conduction band bottom is mainly from the hybrid of C 2s and Si 3p states. The electron density differences indicate that the bond type of Si and C in 6H-SiC are sp3 hybridisation. The calculation results for optical properties show that there is an obvious dielectric peak within the range of energy from 0 to 15 eV, with absorption band edge corresponding to ultraviolet band, therefore, the 6H-SiC material may be a type of excellent ultraviolet semiconductor materials.