Characterization of RF Sputtered-ZnS Thin Film Grown at Various Annealing Temperatures

Abstract

ZnS thin films were deposited onto glass substrates by radio (RF) magnetron sputtering at room temperature. The films were grown at various annealing temperatures in vacuum at the range of 100–350 °C for 60 min. The effects of annealing temperatures on the structural and optical properties of the annealed samples were investigated with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible transmission spectra. XRD patterns of ZnS thin films annealed in vacuum show a single peak at 2 = 28.91° and a preferred orientation along the (111) reflection plane, indicating a zinc blende structure. The intensity of the diffraction peaks is increased with annealing temperatures. FESEM images reveal that the particle size is enhanced from 22.6 nm (at 100 °C) to 48.7 nm (at 350 °C) with increase in the annealing temperatures. The optical band gap of the films shifts to a higher energy and the calculated value shows an increment from 3.27 to 3.51 eV as the growth temperature increases. The structural and optical properties of ZnS thin films are significantly affected by their annealing temperatures.