Six novel silicon carbide with direct bandgaps: A comprehensive study

Abstract

Six new SiC phases with direct bandgaps were found by replacing carbon atoms with carbon and silicon atoms with a stoichiometric ratio of 1:1 in the SACADA-Samara Carbon Allotrope Database of 522 pure carbon structures via the global search method. The six newly discovered SiC phases are in the space groups of Pccn, P4/ncc, Pmn21, P63/m, I4¯3m, and Pnma, in which crystal structures, stabilities, elastic anisotropy, electronic and effective mass were investigated in detail based on first-principles calculations. The formation energies of Pmn21-SiC and Pnma-SiC are very close to that of F4¯3m-SiC, revealing their superiority in experimental implementation. Pccn-SiC, P4/ncc-SiC, Pmn21-SiC, and Pnma-SiC have better compression resistance than F4¯3m-SiC. All the proposed structures are direct bandgap semiconductors with a wide bandgap range of 2.86 ∼ 3.72 eV, which have a smaller effective mass than diamond silicon, giving promising applications in high-frequency, high-temperature and high-power electronic devices.