First principle study on the electronic, elastic and optical properties of ZnS(Se, Te)

The electronic band structure, elastic and optical properties of ZnS(Se, Te) have been studied using first principle method based on the density functional theory (DFT). The calculated elastic physical quantities such as the elastic constants are in good agreement with the experimental values. Results show that Debye temperatures of ZnS, ZnSe and ZnTe at low temperature are 274.725 K, 220.466 K and 162.165 K respectively, which decrease with the increase of anionic radius. Static dielectric constants of ZnS, ZnSe and ZnTe are 4.71, 5.58 and 7.18 respectively. In the low energy region, the real part of dielectric function increases with the increase of the incident photon energy. Among these three semoconductors, ZnTe reaches the highest dielectronic constant (13.78) at the lowest photon energy (3.61 eV). Static refractive indices are 2.17, 2.36 and 2.68, and the maximum refractive indices under external electromagnetic field are n_ZnS(7028 eV)=3.57, n_ZnSe(6.60 eV)=3.56 and n_ZnTe(3.69 eV)=3.82 respectively. The absorption edges are fitted to be 3.7953 eV, 2.9329 eV 2.48765 eV for ZnS, ZnSe and ZnTe respectively via the absorption spectrum coefficient. The results are in good agreement with the experimental values.