Low-temperature phase transition of ZnS: The critical role of ZnO

Wurtzite zinc sulfide (WZ-ZnS) is a valuable wide-band-gap semiconductor. However, it is difficult to synthesize due to its high transition temperature (1020 °C). This study investigates the formation of WZ-ZnS particles using a ZnO template. Various phase structures of ZnS with the same size but different levels of ZnO content are generated during the annealing process. The transition temperature can be lowered significantly to below 350 °C. Furthermore, when the powders of ZnO and zinc-blende ZnS are mixed, large ZnS particles are not induced by ZnO to transform into WZ-ZnS. The results strongly suggest that grain size is an essential but not sufficient factor in the formation of WZ-ZnS at lower temperatures.