Influence of low-temperature sulfidation on the structure of ZnS thin films

ZnS thin films were prepared by sulfuring zinc thin films at different sulfuration temperatures. The crystal structure, surface morphology, defects, and optical properties of the thin films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), positron annihilation Doppler broadening, and UV-Vis spectrophotometer, respectively. It was found that the (200)-plane preferred orientation of the ZnS thin films changed to (111)-plane with increasing sulfidation temperature. Moreover, a number of large holes were generated at 420℃ and eliminated at 440℃. The concentration of defects was lowest when the sulfuration temperature was 440℃. The optical transmission of all samples was maintained at 60%-80% in the wavelength range of 400 nm-800 nm, and the band energy of the ZnS thin films was approximately 3.5 eV for all treatment temperatures except 430℃.