Ab-initio study of Al_1–x Ga _x Sb compound

Abstract

Abstract The ground-state structural, electronic and optical properties of the Al 1– x Ga x Sb compound in the zinc-blende phase for x = 0.125, 0.25 and 0.50 have been stud ied employing the full potential linearized augmented plane wave plus local orbitals method based on the density functional theory. For the exchange-correlation effects we have adopted the GGA approach. In order to model Al 1– x Ga x Sb zincblende alloys, we employ a 16-atoms supercell of the type 2 × 2 × 2. The lattice structures of Al 0.875 Ga 0.125 Sb, Al 0.75 Ga 0.25 Sb and Al 0.50 Ga 0.50 Sb are obtained by replac ing one, two and four Al atoms, respectively, with an equal number of Ga atoms in the crystal lattice of AlSb. The variation of energy band gap of Al 1– x Ga x Sb versus the value of ‘ x ’ reveals that the band gap bowing para m eter has strong composition dependence for small concentrations of Ga. The DOS plots and the various calculated optical properties are in accordance with the calculated electronic properties. The characteristic properties of Al 1– x Ga x Sb are dominated by the Sb 5 p electrons. Linear optical properties such as the dynamic dielectric function, static refractive index, reflectivity and energy loss function for an energy range of 0 to 13.50 eV have been studied. The static dielectric constant increases with the increase in Ga concentration in Al 1– x Ga x Sb. The bulk plasma frequency ω p for this material corresponds to 13.19 eV.