Thesis (M.Sc.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Sciences and Interactions

PbS thin films were deposited on glass substrates using the simplest and low cost chemical bath deposition technique (CBD). Three different lead sources namely lead nitrate, lead acetate and lead chloride have been used for the synthesis with thiourea as sulphur source and sodium hydroxide as a base medium. The effect of change lead sources on structural, surface morphological optical and electrical properties was discussed. According to X-ray diffraction studies, all the films were polycrystalline with face centered cubic structure. The average crystallite sizes were found to be in the range 40-64 nm, Thus, XRD studies reveal that the films deposited by CBD were formed from monocrystalline PbS. AFM images show different morphology for films, The crystalline grains were relatively good, grain sizes were uniformly distributed on the surface of the substrate for film prepared using lead nitrate as a lead source, whereas for samples prepared using lead acetate and lead chloride as a lead sources grain sizes were non uniformly distributed on the surface of the substrate .The SEM photographs showed diverse morphology. The optical band gap is found to be very sensitive to the metal sources used. The direct band gap energy values obtained are in the range of 1.50{u2013}1.77 eV. The Samples prepared using nitrate as metal source from the properties are found to be the best metal source for preparing PbS thin films .For higher thickness the reaction was repeated and the thickness was doubled. The reaction was repeated three times and get four different thicknesses 300,600,900 and 1200nm

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