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.