Penta-silicon carbide: A theoretical investigation

Abstract

Two newly designed penta-silicon carbides, namely p-SiC10 and p-Si4C7, are proposed in this work with the aid of density functional theory (DFT) simulations. Their structural stabilities are verified from energetic, lattice dynamic, and mechanical aspects. These systems possess low mass densities owing to the big interior spaces inherited from the host (i.e., pentadiamond), and relatively high mechanical strengths. The substitutions of the sp3 carbon atoms by silicon in pentadiamond results in the narrowing of the energy band gaps from 3.78 eV to 3.18 eV and 2.81 eV in p-SiC10 and p-Si4C7 lattices at HSE06 level, respectively. Moreover, the band gap changes from indirect in pentadiamond into quasi-direct in p-SiC10. These advantages make p-SiC10 and p-Si4C7 materials be promising candidates in semiconductor industry and aerospace field.