PbS Thin Films Prepared by Chemical Bath Deposition: Effects of Concentration on the Morphology, Structure and Optical Properties

Lead sulfide thin films were prepared at 25 degrees C temperature using chemical bath deposition (CBD) on both Si (100) and glass substrates. XRD analysis of the PbS film shows that the prepared films have a polycrystalline structure with (200) preferential orientation. The grains become smaller with increasing the deposition concentration. X-ray photoelectron spectroscopy (XPS) demonstrated the presence of lead sulfide as PbS. The composition of the prepared films is investigated by energy-dispersive X-ray spectroscopy technique, and it was found that the films are stoichiometric and have low oxygen contamination. Raman and XPS spectra confirm that the CBD method is a decent one to acquire stoichiometric PbS film with nanostructures. Atomic force microscopy was applied to investigate the change in the films morphology with the concentration. The effect of the concentration, on both optical transmittance in the UV-NIR region and the structure of the film, was studied. The results revealed that the optical band gap increased slightly when the concentration increased together with the grain size evolution.