Effect of oxygen content on structural and optoelectronic properties of ZnS1- xOx alloy in the wurtzite structure

Abstract

The tunability of the physical parameters of ZnS1-xOx alloy in the wurtzite phase makes this semiconductor potentially useful as an absorbent layer and antireflection coating. A deviation of the bulk modulus from Vegard's law is observed in ZnS1-xOx alloy. Based on the density functional theory as implemented in the Wien2k code under the virtual crystal approximation, the lattice constant, bulk modulus and band gap have been calculated with both GGA and the modified Becke-Johnson potential (mBJ). The ternary ZnS1-xOx alloy becomes more stable with the increase in the oxygen content x. The in-plane and out-of-plane imaginary components of the dielectric function attain non-zero magnitude at energy identical to the fundamental band gap value. The intense peaks in the in-plane and out-of-plane dielectric function located at 6.5 eV and 7.75 eV suggest inter band transition, and no photon emission in this material. ZnS1-xOx absorbs ultraviolet light in the range 4 eV–10 eV, which validates its candidature for optical and photovoltaic devices. The refractive index is more important when photons move through the material and when bonds between atoms are covalent. The anisotropic optical parameters, the fundamental band gap range (2.7–3.7 eV) and absorption of extreme ultraviolet light make ZnS1-xOx alloy as windows, lenses and absorber material.