Tuning of optoelectronic and transport properties of zinc-blend magnesium chalcogenides through doping of Hg atom(s): The mBJ-GGA+U based first-principle calculations

Abstract

The present first-principle calculations have established the possibility of tuning of structural, optoelectronic and transport properties of direct-band-gap and optically active zinc-blend magnesium chalcogenides through doping of Hg atom(s) at different compositions. The process results a set of thermodynamically stable, direct-band-gap and optically active HgxMg1-xS, HgxMg1-xSe and HgxMg1-xTe semiconductor ternary alloys. Non-linear enhancement in lattice constant (a0), but reduction in fundamental band-gap (Eg) takes place in each system with increasing Hg-composition (x). Electrons and light holes possess much smaller effective-mass compared to heavy holes in each specimen. Calculations show positive Seebeck coefficient and hence p-type conduction property of each ternary alloys. Calculated electronic figure-of-merit shows that ternary alloys are suitable for efficient thermoelectric applications beyond 900 K temperature. Electronic excitations from valence chalcogen-p level to Mg-4s, 3p and Hg-7s levels of conduction band region of band-structure near Fermi-level put significant contributions in diverse optical phenomenon in the UV region, which lead to their compatibility in fabricating diverse UV optoelectronic devices. Oscillator strength, optical energy-gap, skin-depth, optical electronegativity difference, electronic polarizability and diamagnetic susceptibility of each of the considered specimens are also calculated in the present study.