Effect of Annealing Temperature on the Optical and Structural Properties of As₄₀Se₅₀Ge₁₀Thin Films

The present paper reports the decrease and increase of optical band gap from the pristine value upon annealing at below and above glass transition temperature of the sample. The thin films of As40Se50Ge10 with 800nm thickness were annealed at 140 degrees C and 180 degrees C. The structural characterization was done by X-ray diffraction and Raman spectroscopy. The optical transmission data was recorded by UV-Visible spectrometer in the wavelength range of 400-1100 nm. The indirect optical bandgap was found to decrease and again increased with change in annealing temperature. The films remain in amorphous state irrespective of the optical change and Raman shift. The surface morphology and composition of the film was checked in FESEM study.