First Principles Study of Electronic and Optical Properties of Magnesium based Chalcogenides

The electronic and optical properties of MgSxX1-x (X =Se, Te), and MgSexTe1-x (0 ≤ x ≤ 1) ternary alloys are investigated using the full potential linearized augmented plane wave (FP-LAPW) method within the density functional theory (DFT). The direct band gap energies vary in the ranges 2.854–3.864 eV, 2.470-3.864 eV, and 2.470-2.854 eV for MgSxSe1-x, MgSxTe1-x, and MgSexTe1-x, respectively. These band gaps show a closer agreement with the experimental observations than the calculations by Hassan and Amrani [J. Phys. Condens. Matter 19, 386234 (2007)] using the same potential. Dielectric constants of the alloys are found to vary inversely with dopant concentrations as well as band gaps. Concentration dependent optical conductivity and reflectivity of the same alloys are also discussed.