The Mechanical and Electronic Properties of Carbon-Rich Silicon Carbide

A systematic investigation of structural, mechanical, anisotropic, and electronic properties of SiC(2) and SiC(4) at ambient pressure using the density functional theory with generalized gradient approximation is reported in this work. Mechanical properties, i.e., the elastic constants and elastic modulus, have been successfully obtained. The anisotropy calculations show that SiC(2) and SiC(4) are both anisotropic materials. The features in the electronic band structures of SiC(2) and SiC(4) are analyzed in detail. The biggest difference between SiC(2) and SiC(4) lies in the universal elastic anisotropy index and band gap. SiC(2) has a small universal elastic anisotropy index value of 0.07, while SiC(2) has a much larger universal elastic anisotropy index value of 0.21, indicating its considerable anisotropy compared with SiC(2). Electronic structures of SiC(2) and SiC(4) are calculated by using hybrid functional HSE06. The calculated results show that SiC(2) is an indirect band gap semiconductor, while SiC(4) is a quasi-direct band gap semiconductor.