The Mechanical and Electronic Properties of Carbon-Rich Silicon Carbide

A systematic investigation of structural, mechanical, anisotropic, and electronic properties of SiC₂ and SiC₄ 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 SiC₂ and SiC₄ are both anisotropic materials. The features in the electronic band structures of SiC₂ and SiC₄ are analyzed in detail. The biggest difference between SiC₂ and SiC₄ lies in the universal elastic anisotropy index and band gap. SiC₂ has a small universal elastic anisotropy index value of 0.07, while SiC₂ has a much larger universal elastic anisotropy index value of 0.21, indicating its considerable anisotropy compared with SiC₂. Electronic structures of SiC₂ and SiC₄ are calculated by using hybrid functional HSE06. The calculated results show that SiC₂ is an indirect band gap semiconductor, while SiC₄ is a quasi-direct band gap semiconductor.