Thermal annealing effect on the optical properties of Ag10As30S60 thin film

Chalcogenide Ag10As30S60 thin films are prepared using the thermal evaporation technique from the bulk alloy. Deferential Scanning Calorimetry (DSC) curve reveals two crystallization stages for the bulk. The X-ray examination of the as-prepared and annealed films shows that the sample is crystallized in preferential orientations indicated with peaks corresponding the S8 and ternary AsAg3S3 phases. Transmission spectra show that the as-prepared and annealed films have highly transparent over the visible region. The presence of a sharp absorption edge for all films in the transmission spectra recommends Ag10As30S60 thin films as a good optical filter material. The improvement in transparency upon annealing is due to the enhancement in the crystallinity. The decrease in both optical band gap and refractive index of annealed films after crystallization temperatures is discussed in accordance with the structure changes upon annealing.