Structural investigation of Si0.5Ge0.5 alloy for optoelectronic applications: Ab initio study

Abstract

The structural, electronic and optical properties of the binary silicon–germanium alloy have been investigated using the projector augmented-wave (PAW) calculations with a powerful VASP package (Vienna ab initio simulation package). The structural properties of Si0.5Ge0.5 alloy have been calculated using total energy calculations and compared with our empirical model of bulk modulus. The electronic band structure and density of state of Si0.5Ge0.5 alloy show that the conduction band minimum (CBM) is located at the X point and the valence band maximum (VBM) is located at the Г point, resulting in indirect (Г–X) energy band gap of 0.48eV. The results of the refractive index and optical dielectric constant of Si0.5Ge0.5 alloy are also obtained. The PAW's results are in good agreement with experimental, theoretical and our model results.