الفهرس 
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Abstract
PbS thin films were deposited on glass substrates by chemical bath deposition method. The effect of varying the film thickness on the structural and optical properties has been investigated. The crystal structure was characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscope (SEM). X-ray analysis reveals that, all films were polycrystalline with a cubic rock salt structure with (200) preferred crystal orientation. Increasing the film thickness enhances the crystallinity of the films as well as decreases the strain and dislocation density. The morphological properties of the films were investigated by scanning electron microscopy. The surface of the films was dramatically changed from small spherical grains to beads like shape. The absence of impurities in the deposited films were confirmed by energy dispersive x-ray spectrometry (EDX) measurements.
The optical properties of the films were studied using the transmittance and reflectance spectra. The optical band gap of the films decreased from 2.75 eV to 2.34 eV with increasing the film thickness. The optical parameters of the materials such as refractive index, extinction coefficient and dielectric constants were also determined.
The conductivity measurements were carried out through the temperature range (313-543 K) for PbS films. The electrical conductivity of the PbS film increased with increasing film thickness. The activation energy (Ea) decreased from 0.27 eV to 0.17 eV as the film thickness increased.