OPTICAL AND STRUCTURAL PROPERTIES OF SILAR-GROWN HIGHLY ORIENTED LEAD SULPHIDE (PbS) THIN FILMS

The lead sulphide (PbS) thin films were deposited on a glass substrate using successive ionic layer absorption and reaction (SILAR) method at different number of cycles at a room temperature using lead nitrate, thiourea, and sodium hydroxide as chemical precursors. The optical and structural studies was performed by UV-VIS spectrophotometry, X-ray diffraction (XRD) and SEM. The XRD showed films of cubic (galena), crystalline in nature with the preferential (111) orientation. The PbS thin films obtained under optimal deposition conditions were found to polycrystalline with face centered cubic structure. The lattice parameter, grain size, were calculated. The values of the average crystalline sizes were found to be in the ranges of (7-15) nm. Optical studies was carried out using UV spectrometer and it revealed the existence of direct band gap values in the ranges of (1.58-1.70) eV.