Theoretical investigation of group-IV binary compounds in the P4/ncc phase

Abstract

Three direct and two indirect semiconductor materials together with one metallic material for group-IV binary compounds in the P4/ncc phase are investigated in this work, by employing density functional theory (DFT), where the morphology, stability, mechanical anisotropy, electronic properties, effective mass and optical properties are obtained. SiC, SnC and SnSi are all semiconductor materials with direct bandgaps of 3.38 eV, 1.30 eV and 0.67 eV, respectively, while GeC and GeSi have indirect bandgaps of 2.86 eV and 1.14 eV, respectively. The formation energy of P4/ncc-SiC is −133 meV per atom, indicating its excellent thermodynamic stability and great promise for future experimental realization. P4/ncc-SiC is more incompressible than C2/m-SiC and P42/mnm-Si8C4, and P4/ncc-GeSi is more incompressible than h-GeSi. SnSi has the largest anisotropy in the Young’s and shear modulus, SiC and GeC have the largest anisotropy in the Poisson’s ratio. P4/ncc-SnSi and SnC have low electron effective masses of 0.08m0 and 0.09m0, respectively, which may indicate a high carrier transport property. Compared with Fd-3m-Si, SnSi and GeSi show better optical absorption properties for infrared and visible light regions. All these unique properties endow these materials with great promise for application in microelectronic and optoelectronic devices.