An ab-initio study of structural,opto-electronic and thermoelectric aspects of zinc sulfide and zinc telluride

In this study, structural, electronic, optical and thermoelectric aspects of Zinc Sulfide (ZnS) and Zinc Telluride (ZnTe) have been explored in detail. These calculations have been done by utilizing FP-LAPW method via Density Functional Theory (DFT). In order to attain accurate band gaps, opto-electronic properties are evaluated with modified Becke Johnson potential (mBJ). From band structure plots, both ZnS and ZnTe reveals direct (Γ_v–Γ_C) band gap semiconductors in nature with bandgap value equal to 3.5 and 2.3 eV while in Density Of States (DOS) major influence is observed due to p states of S/Te and d state of Zn. Prominent variation of optical responses such as high values of imaginary dielectric constants 𝜀1 (ω) and n (ω) refractive index suggests that ZnS and ZnTe are applicant materials for future photonics and microelectronic devices. The thermoelectric aspects were explored by Boltz Trap code to determine electrical and thermal conductivities, Seebeck coefficients, power factors and figure of merit. The figure of merits is closer to 1 while compared with p-type ZnS and ZnTe, n-type ZnS and ZnTe has good thermoelectric properties, which are attributed to low thermal conductivity of the hole and larger effective mass. The goal of this research is to investigate not only the detailed physical aspects but also to provide an overview of its future applications in optoelectronics, displays, sensors and microelectronic industry.