Optical and electrical properties of amorphous Sb2S3 thin films: Effect of the film thickness

The antimony tri-sulphide (Sb2S3) films were prepared by thermal evaporation technique. Four thicknesses (300, 521, 643 and 789 nm) were investigated. X-ray diffraction (XRD) analysis showed the amorphous structure of Sb2S3 films. Optical analyses revealed that Sb2S3 films exhibited optical energy gap between (1.98–1.16 eV) relaying on the film thickness. The films absorption coefficient was found to be higher than 2 × 104 cm−1(above its related optical energy gap) which makes these films reliable absorbers in photovoltaic applications. Optical constants were analyzed using Swanipole's method. The dark dc conductivity measurements of Sb2S3 thin films were conducted in the temperature range 298–503 K. The conduction mechanize was analyzed via Mott's variable -range hopping in three dimensions model. The correlated conductivity mechanize with increasing film thickness changed from extended states to localized states. The results revealed that both optical gap and activation energy decreased as the film thickness enhanced.