Optical constants and electrical conductivity of Ge20Se60Sb20 thin films |
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Authors: | A A Abu-Sehly |
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Affiliation: | (1) Physics Department, Faculty of Science, Assiut University, Assiut, Egypt |
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Abstract: | Optical absorption and electrical resistivity of amorphous Ge20Se60Sb20 films are investigated as a function of the thermal annealing. The dependence of the optical absorption coefficient on the photon energy is ascribed by the relation ( h ) = B(h –Eo)2. Increasing the annealing temperature from 423 K to 553 K, decreases the optical gap of the film from 1.25 eV to 0.78 eV. The effect of annealing temperature on high frequency dielectric constant (![isin](/content/j1535580429h7q51/xxlarge8712.gif) ) and carrier concentration (N) was also studied. As a result of annealing the film at 533 K, the electrical resistivity and activation energy for conduction decreased from 5.7 × 107 to 2.9 × 102 ![OHgr](/content/j1535580429h7q51/xxlarge937.gif) · cm and from 0.94 to 0.34 eV, respectively. The crystalline structures resulting from heat treatment at different elevated temperatures have been studied by X-ray Diffraction (XRD). The optical and electrical changes were attributed to the amorphous-crystalline transformations in the chalcogenide films. |
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