Abstract
Amorphous Ge30Sb10Se60 chalcogenide thin films were prepared onto cleaned glass substrates using thermal evaporation technique. The structure of the as-prepared films was confirmed to be amorphous using X-ray diffraction. The optical absorption coefficient (alpha) for the as-deposited films was calculated by using reflectance and transmittance measurements in the wavelength range 400-900nm. The optical constants (refractive index (n) and the extinction coefficient (k) were controlled by Murman's exact equations. The effects of annealing temperature in the temperature range 300-658 K on the optical and electrical properties of the as-prepared Ge30Sb10Se60 thin films were discussed in details. It was found that both the optical band gap E-g(opt) and the activation energy for electrical conduction Delta E-dc increase with increasing the annealing temperature up to the glass transition temperature (T-g), followed by a remarkable decrease with the increase of annealing temperature above T-g. The obtained results were interpreted on the basis of amorphous-crystalline transformations. (c) 2007 Elsevier B.V. All rights reserved.