Physics Department, Faculty of Science, South Valley University, 82524 Sohag, Egypt
Chalcogenide glasses with Ge10As x Te90−x (x = 20, 25, 30, 35, 40, 45 and 55 at.%) were prepared by melt quenching technique. The glass transition temperature, the crystallization temperature, the melting temperature and the glass-forming tendency were determined from the differential scanning calorimetry measurements. The structural and optical properties of Ge10As x Te90−x thin films prepared by electron beam evaporation were studied. X-ray diffraction showed that the as-evaporated films are amorphous and crystallize after annealing depending on the As content. The transmittance and reflectance of the films are found to be thickness dependent. The optical-absorption data indicate that the absorption mechanism is direct transition. The optical band gap values are increased with increasing As content while they decrease with increasing the film thickness. Upon annealing the transmittance and the optical band gap decrease whereas the reflectance and the refractive index increase.
(Received October 29 2005)
(Revised January 27 2006)
(Accepted March 17 2006)
(Online publication June 24 2006)