First-principles calculations to investigate transformation of optically inactive zinc-blend beryllium chalcogenides to optically active semiconductor alloys through doping of Hg atom(s)

Abstract

First-principle calculations show transformation of indirect-band-gap zinc-blend beryllium chalcogenide to direct-band-gap mercury-beryllium-chalcogenide HgxBe1-xS, HgxBe1-xSe and HgxBe1-xTe semiconductor ternary alloys through doping of Hg atoms at different concentrations. The lattice constant increases but fundamental band-gap reduces nonlinearly in each system with increasing mercury-composition. Effective mass of electrons is much less than that of holes in each specimen. Computed thermoelectric properties of ternary alloys show their p-type conductivity and also their compatibility in thermoelectric applications in the 400–1200 K temperature range. Peaks in the dielectric function spectra of ternary alloys in the UV region are originated from chalcogen-p level of valence band to Be-3s, 2p and Hg-7s levels of conduction band and they confirm their compatibility in UV optoelectronic applications. Calculated static optical constants of the specimens under any ternary system decrease with increasing band-gap and vice versa. Oscillator strength, optical energy-gap and skin-depth of ternary alloys have also been calculated.