Investigation of molybdenum dopant effect on ZnS thin films: Chemical composition, structural, morphological, optical and luminescence surveys

Zinc sulfide (ZnS) thin films are prepared by chemical bath deposition (CBD) method on glass substrates. The effect of molybdenum (Mo) doping concentration on chemical composition, structural, morphological, optical and luminescence properties of zinc sulfide thin films is investigated. Chemical composition study by X-ray fluorescence (XRF) confirms the presence of molybdenum in the deposited films. Structural analysis by means X-ray diffraction (XRD) shows that Mo doped ZnS (Mo:ZnS) films crystallize into cubic crystalline structure with (111) preferred crystallographic orientation. X-ray photoelectron spectroscopy (XPS) proves the formation of ZnS by showing the Zn 2p and S 2p spin-orbit doublets. The incorporation of Mo is confirmed by the detection of Mo 3p and Mo 3d lines. Fourier transform infrared (FTIR) spectroscopy reveals some impurities adsorbed on the films surfaces. Mo dopant induces also changes in the surface morphology of the studied films. The optical properties are enhanced for 6 at.-% Mo doping concentration in both visible and infrared regions. The refractive index n(λ) and the extinction coefficient k(λ) are estimated revealing transparency feature for the elaborated films. Photoluminescence intensity quenching is found by Mo incorporation.