Impact of selenium (Se) substitution on the structural, electronic, transport and optical characteristics of wurtzite zinc telluride semiconducting compound for optoelectronic applications: a first-principles approach

Abstract

This study investigates the electronic, transport and optical properties of selenium-doped zinc telluride (ZnSe_xTe_1−x) ternary alloys in the hexagonal wurtzite (B4) phase at varying selenium concentrations using DFT-based FP-LAPW methods at (x = 0.0, 0.25, 0.50, 0.75, 1.0). Structural properties were calculated using the WC-GGA functional, while electronic, transport and optical properties were computed using the mBJ-GGA functional. All the specimen exhibits direct bandgaps with a Γ–Γ transition. The lattice constants (a and c) decrease nonlinearly with more selenium, while the bulk modulus (B) and bandgap (E_g) increase. The electronic transport properties were evaluated through the Seebeck coefficient, electrical conductivity, electronic thermal conductivity and electronic power factor. Additionally, the optical properties due to scattering were computed, and the results reveal the optically anisotropic nature of all the studied alloys, with birefringence clearly observed. The optical energy gap (E_opt) of each ternary alloy lies in the UV region, promising for UV optoelectronic device applications.