Microstructure and Near Infrared Absorption of PbS Films Deposited by Chemical Bath Deposition on p-Type Si(100) Wafers

Nanocrystalline PbS films were synthesized on p -type Si(100) wafers using chemical bath deposition. All of the PbS films are polycrystalline in nature with face -centered cubic (fcc) rock salt structure. The average crystallite size varied from 20 to 74 nm, thereby indicating nanocrystalline films with different molar ratios. The film composed of irregular particles was homogeneous and well adhered to the substrates. Increase in thiourea concentration from 0.5 to 2.0 M resulted into an increase in the lateral particle size and film thickness, while further increase in thiourea concentration caused a decrease in particle size and film thickness. The absorption edge of the films blueshifted slightly with increased molarities of lead sources, blueshifted initially, and then redshifted with increased molarities of sulfur sources at a fixed lead source molarities. The blueshift and redshift of the absorption edge were closely related to the change in the tensile stress of the PbS films subjected to.