PREDICTING STABLE CRYSTAL STRUCTURES AND THEIR ELECTRONIC PROPERTIES OF Si-RICH SILICON CARBIDE BY FIRST PRINCIPLE CALCULATION

Abstract

Silicon carbide has become an attractive semiconductor material with its high stability. It has been used in variety of fundamental aspects and applications such as photovoltaic solar cells due to its unique properties, for instances high thermal conductivity and low density. Investigating thermodynamically stable non-stoichiometric silicon carbide structures can be useful as they can be used in applications without requiring a pure grade of silicon or pure grade of silicon carbide materials. Density functional theory (DFT) calculations were used to examine the stability of various structures of silicon carbide such as 2H-SiC, 4H-SiC, 6H-SiC, wurtzite structure, FeSi structure, and diamond structure of SiC. We investigated different configurations of silicon and carbon atoms in these silicon carbide structures to obtain suitable silicon rich silicon carbide materials with tailored band gap. We have studied the electronic structures of these structures. We have replaced the carbon atoms by silicon atoms to lower the band gap of the silicon carbide. Total energies of these structures, as well as the formation enthalpies of silicon incorporations have been calculated by density functional theory.