Characterization of cerium-doped zinc sulfide thin films synthesized by sol-gel method

Thin films of un-doped and cerium (Ce)-doped zinc sulfide (ZnS) with various doping concentrations of Ce (2, 4, 6, 8 and 10 at. %) were prepared and deposited on glass substrates by sol-gel process and dip-coating method. The effects of different Ce doping concentrations on the structural, morphological, optical, and photoluminescence properties of such films were studied using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), UV-visible spectrophotometry, and photoluminescence (PL) spectroscopy. XRD patterns exhibited an amorphous structure for all the synthesized films. FTIR analysis confirmed the presence of the Zn-S band. AFM revealed that the samples presented a smooth and homogenous structure. SEM micrographs showed that the surface morphology of the films was affected by the doping with Ce concentrations. According to the UV-visible spectroscopy measurement, all the films were highly transparent with average visible transmittance values ranging from 60 to 85%. Room temperature PL spectra showed the presence of two peaks in the ultraviolet domain and four very weak emission bands in the visible range.