Substrate Effects on the Structural Properties of Thin Films of Lead Sulfide

Nanocrystalline PbS thin films are deposited on glass and alumina substratesthrough the chemical bath deposition technique by creating similar conditions, in orderto investigate the effects of the substrate. The structural and optical properties of PbSfilms are investigated by X-ray diffraction, scanning electron microscope, and UV–Vis.The structural analyses of the films indicate that they are of polycrystallineconfigurations and have a face-centered-cubic (fcc) rock-salt structure on differentsubstrates. The X-ray diffraction shows that the structure peaks occur at slightly higherangles in the deposited (grown) films on glass substrate than the ones deposited onalumina substrate. Crystal parameters are exceptionally affected by the type of substrateas well. SEM images reveal that the surface morphology of the PbS thin films is quitedependent upon the nature of the substrate. The optical band gaps of the samples arefound to be 1.521 eV for glass and 1.678 eV for alumina substrates, which are higher incomparison to the bulk value (0.41 eV). According to the obtained results, PbS thin filmon alumina substrate has narrower particle size distribution, better transmission andlower stress than PbS thin film on glass substrate.