“…Among them, zinc sulfide (ZnS) is an important binary II-VI semiconductor compound with a direct wide band gap energy of 3.6-3.7 eV at room temperature [2,3,4,5] and a high refractive index, as well as a high transmittance in the visible region [6]. ZnS has been widely used in numerous optical applications such as ultraviolet light-emitting diodes [7], flat panel displays [8] and thin-film electroluminescent devices [9,10].…”