Effect of p–d hybridization, structural distortion and cation electronegativity on electronic properties of ZnSnX2 (X=P, As, Sb) chalcopyrite semiconductors

Significant effects of p –d hybridization, structural distortion and cation-electro-negativity are found on band gap in ZnSnX 2 (X =P, As, Sb). Our study suggests these compounds to be direct band gap semiconductors with band gaps of 1.23, 0.68 and 0.19 eV respectively. Lattice constants, tetragonal distortion (η)(η), anion displacement, bond lengths and bulk moduli are calculated by Density Functional Theory based on Tight binding Linear Muffin-Tin orbital method. Our result of structural properties is in good agreement with the available experimental and other theoretical results. Calculated band gaps also agree well with the experimental works within LDA limitation. Unlike other semiconductors in the group II–IV–V2, there is a reduction in the band gap of 0.22, 0.20 and 0.24 eV respectively in ZnSnX 2 (X =P, As, Sb) due to p –d hybridization. Structural distortion decreases band gap by 0.20, 0.12 and 0.10 eV respectively. We find that cation electronegativity effect is responsible for increasing the band gap relative to their binary analogs GaInP2GaInP2, InGaAs2InGaAs2 and GaInSb2GaInSb2 respectively and increment are 0.13, 0.04 and 0.13 eV respectively.