Structural and the optical characteristics of PbS_x thin films

PbS_x thin films (x = 1, 0.9, 0.8, 0.7, 0.6) were prepared onto glass substrates using spin coating method. The phases developed and vacancies created in the different films were explored employing θ-θ scan X-ray diffraction, grazing incidence X-ray diffraction, and Fourier transform infrared techniques. The possibility of incorporation of oxygen in PbS lattice was also examined using X-ray photoelectron spectroscopy technique. Rietveld analysis was achieved to determine the variation in the structural and microstructural parameters of different films. The morphology and thickness of the films were explored using scanning electron microscope technique. The direct band gap transition values for PbS_x films with x = 1, 0.9, 0.7 and 0.6 are 2.63, 2.85, 2.95, and 3.02 eV, respectively. The refractive indices of all films demonstrated a normal dispersion. The effect of sulfur reduction in the formed films on the optical absorbance, reflectance spectra, absorption edge, extinction coefficient, dielectric constant, photoluminescence emitted colors, and nonlinear optical parameters of the PbS_x films was investigated.