Structure, optical and electrical properties of Ge30Sb10Se60 thin films

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 (α) for the as-deposited films was calculated by using reflectance and transmittance measurements in the wavelength range 400-900 nm. 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 Egopt and the activation energy for electrical conduction ΔEdc increase with increasing the annealing temperature up to the glass transition temperature (Tg), followed by a remarkable decrease with the increase of annealing temperature above Tg. The obtained results were interpreted on the basis of amorphous-crystalline transformations.