Theoretical study of structural, electronic, optical and elastic properties of Al _x Ga _1−x P

In this work, the structural, electronic and optical properties of pure and aluminum (Al) doped gallium phosphide (GaP) in zinc-blende (ZB) phase are elaborated using full potential linearized augmented plane wave (FP-LAPW) method as implemented in Wien2K code. The calculated lattice parameters show decreasing behavior with increasing the concentration of Al contents. Band gaps of Al _x Ga _1−x P are investigated by generalized gradient approximation (GGA) and found to be the increasing linear behavior by increasing the concentration of Al. Furthermore, the optical properties including dielectric constants, refractive index, reflection coefficient, absorption coefficient and extinction coefficient of Al _x Ga _1−x P at different compositions are also calculated and discussed. In order to check the mechanical behavior under the influence of applied pressure the elastic coefficients of all these composition have been calculated and discussed. Calculated parameters i.e. lattice constants, band gaps, and optical variables are very close to the experimental values which suggested that the materials are good candidates for the opto-electronic devices. Further, the elastic constants for all compounds which describes the mechanical behavior are reported for the first time and there is no data available for comparison.