Structural and Optical Properties of GaAs_0.5Sb_0.5 and In_0.5Ga_0.5As_0.5Sb_0.5: ab initio Calculations for Pure and Doped Materials

We perform a first-principles study to evaluate the structural, electronic and optical properties of GaAs_xSb_1−x ternary and In_yGa_1−yAs_xSb_1−x quaternary semiconductor alloys up to x = 0.5, y = 0.5. We employ the Perdew-Burke-Ernzerhof form of the generalized gradient approximation (GGA) within the framework of density functional theory (DFT) by using a simulation program. Calculations are carried out in different configurations. For these alloys, lattice parameters and optical band gap energy are calculated. The optical band gaps vary with increasing and decreasing As and In concentrations, respectively. The optical conductivity, absorption and the real part of the dielectric function ∊₁(ω) are discussed. Our results agree well with the theoretical and experimental data available in the literature.