Structural and optical properties of amorphous Sb2S3 thin films deposited by vacuum thermal evaporation method

Sb₂S₃ thin films have been deposited by vacuum thermal evaporation onto glass substrates at various substrate temperatures in the range of 30–240 °C. Crushed powder of the synthesized Sb₂S₃ was used as raw material for the vacuum thermal evaporation. The structural investigation performed by means of X-ray diffraction (XRD) showed that the all as-deposited films present an amorphous structure and all the films were highly resistive. The reflectance and transmittance of the films are measured in the incident wavelength range 300–1800 nm. The absorption coefficient spectral analysis revealed the existence of long and wide band tails of the localized states in the low absorption region. The band tails width is calculated and found to be varying between 0.024 and 0.032 eV. The analysis of the absorption coefficient in the high absorption region revealed two direct forbidden band gaps between 1.78–1.98 eV and 1.86–2.08 eV.