Effect of thermal annealing in vacuum on the structural and optical properties of Sb2S3 thin films

In this work, the effect of the thermal annealing on the structural and optical properties of antimony trisulfide (Sb₂S₃) thin films deposited by thermal evaporation onto glass substrates held at 293 K was studied. Sb₂S₃ thin films were annealed at 500 K for 1 h in vacuum. Their structural properties have studied by transmission electron microscopy (TEM). The TEM analysis showed that the as-deposited Sb₂S₃ thin films have been an amorphous structure, while after annealing treatment, they become polycrystalline in structure. The optical constants of Sb₂S₃ thin films as refractive index, n, and absorption coefficient, α, were obtained from the analysis of the experimental recorded spectral transmission data over the wavelength range of 500-1400 nm. From the photon energy dependence of absorption coefficient, the optical band gap energy, E_g, was calculated for both the as-deposited and annealed Sb₂S₃ thin films.