Effect of doping concentration on the structural, morphological and optical properties of Ca-doped PbS thin films grown by CBD

Pure and calcium doped lead sulfide (PbS) thin films were prepared by chemical bath deposition (CBD) method. The effects of calcium doping content on their structural, morphological and optical properties were investigated by X-Ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and UV-vis spectroscopy measurements, respectively. According to X-Ray diffraction patterns all films were polycrystalline in nature, with a cubic crystal structure. It was observed from SEM analysis that calcium doping level affected the film morphology and surface roughness. Incorporation of Ca was confirmed from Energy dispersive X-Ray analysis results. Tauc method was used to estimate the optical band gap energies (Eg) of the pure and calcium doped films. UV-vis analysis showed that the transmittance of the samples varied between 15.3 and 20%. Also, it was observed that transmittance of deposited films increased with adding of calcium. Further, the optical energy band gap values were found to enhance (1.92-2.50 eV) with increasing the Ca content in PbS films.