EFFECT OF THICKNESS ON STRUCTURAL AND OPTICAL PROPERTIES OF THERMALLY EVAPORATED CADMIUM SULFIDE

about 2х10 torr. X-ray diffraction and SEM (scanning electron microscope) were used to characterize the thin films. X-ray diffraction study showed that, all the films have the hexagonal wurtzite structure, with lattice constants a=b=4.142, c=6.724A ̊. Crystallite sizes calculated from Scherrer relation are in the range of 49-68 nm and the grain size of the thin films are observed to increase with the increase in the thickness of the sample. The optical properties of the polycrystalline thin films were investigated by the UV-VIS-NIR spectroscopy. The band gap of the thin films is found to be direct allowed transition and increases with the increase of thickness of films in the range of 2.352.46 eV. Extinction coefficient k showed oscillatory behavior in lower band edge region. The CdS polycrystalline thin films are suitable for solar cell application. 5 −