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Paper Details

Effects of thickness on the structural and optical properties of thermally evaporated CdTe thin films

S.S.Patil * and P.H.Pawar

Journal Title:Journal of Chemical, Biological and physical sciences

CdTe thin films of different thicknesses on glass substrates have been prepared by thermal evaporation technique at room temperature in vacuum (?10-5Torr). The selected samples were annealed at 573 K for 30 min. in vacuum (?10-5Torr).The X-ray diffraction (XRD) patterns of the annealed CdTe samples with five different thicknesses were recorded by X-ray diffractometer. The XRD patterns exhibits polycrystalline nature which suggests that these CdTe films are of zinc blende structure with a preferential orientation along the (111) plane of cubic phase. The degree of such a preferred orientation was found to increase with film thickness. The crystallite size (D), dislocation density (?) and strain (?) were calculated. The lattice parameter values obtained are a ? 6.47 and a ? 6.50 . The reflectance and transmittance spectra of these samples were recorded using double beam spectrophotometer in the spectral range of 2002700 nm. The fundamental optical parameters like absorption coefficient (?) and band gap are calculated from the transmission spectra. The possible optical transition in these films is found to be direct and allowed. By using the reflectance and transmittance data, the refractive indices (n) and extinction coefficients (k) have been evaluated and discussed graphically.