الفهرس 
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Abstract
The alloys Cu1.8 Se1-x Sx were prepared from Spec. pure elements (5N) in stoichiometric ratio by fusion method. Films of the same thickness (200nm) were deposited on a glass substrate by thermal evaporation technique and annealed at 500K for 2 hour. The composition constituents of prepared samples were determined by Energy ¬Dispersive X-ray analysis (EDAX). The composition of alloys has approximately the composition of starting material with error about 0.03%. XRD data confirmed that all prepared Bulks are formed in cubic system with a space group Fm3 m with deviation in cell parameter depending on the Sulfur content and there are no excess peaks to reveal other phases. The lattice parameter (a) varies linearly with the change of sulfur content but the crystallite size D departs from a linear relation. All d -values of different compositional thin films of thickness 200nm are well matching with their ingot bulks and then formed in single-phase cubic system ((3-Cu1.8Se), but films of thickness 400nm whether annealed or not are formed in two-phase (3-Cu1.8Se (cubic) and a-Cu2Se (monoclinic). GIXRD data confirmed that all prepared thin films by inert gas condensation technique (IGC) are nanocrystalline and formed in single-phase cubic with a preferred orientation (220), but with a small deviation in cell parameter depending on the sulfur content. The electrical data revealed that the all prepared samples show p-type conduction and σ, P, Q decrease as the Sulfur content (x) increases for bulk and thin films. The Hall mobilit3 (µH) decrease as sulfur content increase for bulk materials and increase in case o: polycrystalline thin films. The nanocrystalline thin films of thickness 100nm have large] particle size than those of thickness 60nm which reflects a decreasing of the electrical conductivity by one order of magnitude. The absorption coefficient of different compositional thin films and nanocrystalline thin films were determined from the transmission and reflection in the wavelength range (20( -2500) nm at room temperature. The analysis of the absorption coefficient data revealed the existence of two optical transition mechanisms: allowed direct transition increases from 2.22eV to 2.50eV as the sulfur content(x) increases from 0.25eV to 0.70eV and increase; with annealing from 2.28eV to 2.56eV as the sulfur content increases and indirect transition increases from 1.23eV to 1.52eV as the sulfur content increases. There are also two transitions in nanocrystalline thin films, which are direct and indirect transition and are higher than those of polycrystalline thin films. Both transitions increase as the particle size decrease.