DFT based FP-LAPW investigation of structural, electronic and optical properties of SrxPb1−xS, SrxPb1−xSe and SrxPb1−xTe ternary alloys

Abstract

The structural, electronic and optical properties of SrxPb1−xS, SrxPb1−xSe and SrxPb1−xTe semiconductor ternary alloys for 0 ≤ x≤ 1 in their rock-salt (B1) crystallographic phase have been calculated using the full-potential linearized augmented plane wave (FP-LAPW) method under the framework of density functional theory (DFT). Using the Wu-Cohen generalized-gradient approximation (WC-GGA) induced exchange-correlation potential scheme, the ground state structural parameters have been calculated. Electronic properties of the binary compounds and their ternary alloys have been calculated mainly using Tran-Blaha modified Becke-Johnson (TB-mBJ) parameterization scheme. The atomic and orbital origin of different electronic states in the band structure of each of the compounds have been identified from their respective density of states (DOS). Using the approach of Zunger and co-workers, the microscopic origin of band gap bowing has been discussed in term of volume deformation, charge exchange and structural relaxation. Bonding characteristics among the constituent atoms of each of the specimens have been discussed from their charge density contour plots. Optical properties of the binary compounds and their ternary alloys have been calculated in terms of their respective dielectric function, refractive index, reflectivity and optical conductivity. Some calculated results are compared with available experimental and other theoretical results.