Numerical analysis of uniaxial strain-induced modifications of the band structure and optical properties of zinc toluidine semiconductor

Abstract

The electronic band structure and optical properties of zinc telluride (ZnTe) were studied under hydrostatic pressure using analytical deformation potential theory and first-principles density functional theory (DFT) calculations. The study showed that the band gap energy (Eg) increases linearly with pressure for up to about 15-20 GPa. The average pressure gradient is 45-55 meV/GPa. The compressed Zn-Te lattice has increased orbital overlap and shortened bond length, which raises the CBM and lowers the VBM. This explains the behaviour. Optical calculations reveal a blue shift of the absorption edge which indicates that moderate pressure improves the transmission energy of photons and the quantum efficiency. The electronic structure indicates that a zinc-alloy to rock-salt structure phase transition is originating at pressures above 10-12 Gpa. The transition could close band gap and also take it from direct to indirect transition. The study shows that zinc telluride's (ZnTe) electrical and optical response can be changed using external pressure as a tunable parameter, without using chemical doping. These results provide crucial insights for the design of optoelectronic devices to III-VI semiconductors.