Effect of substrate temperature on the structural, morphological, and optical properties of Sb2S3 thin films

Sb2S3 thin films have been deposited by single source vacuum thermal evaporation onto glass substrates. The substrate temperature was varied in the range of 25-270 °C. X-ray diffraction (XRD) showed that films deposited at substrate TS < 250 °C have an amorphous structure, while those prepared at TS ≥ 250 °C have a polycrystalline structure. XRD investigations showed that the crystallite size dimension increases with increasing substrate temperature. The effect of substrate temperature on grain size and surface roughness was studied by atomic force microscopy (AFM). The optical constants of the films were determined from optical transmission recorded in the 500-1800 nm wavelength range. The dispersion parameters and the high-frequency dielectric constant were determined by modeling the refractive index using the Wemple-Di Domenico model. The optical band gap energy of the films decreases from 1.98 to 1.74 eV as the substrate temperature varies from 25 to 270 °C.