Grain growth and structural transformation in ZnS nanocrystalline thin films

Fabrication of ZnS thin films having similar stoichiometry at different substrate temperatures (TS) e.g. 200 °C, 300 °C and 400 °C by means of RF magnetron sputtering method is presented. The films grown at TS of 200 °C are in cubic zinc-blende phase and textured along (111) plane. The films deposited at TS of 300 °C and 400 °C are in hexagonal wurtzite phase. The surface roughness and grain size of the films increase with increasing TS. The ultra-violet and visible absorption studies show that the bandgap of films can be tailored by varying TS, taking advantage of the structural transformation.