Effect of silver doping on structural and optical properties of In2S3 thin films fabricated by chemical pyrolysis

Silver doped indium sulphide thin films (In2S3:Ag) were deposited by spray pyrolysis technique on glass substrates at temperature 350 °C. The films were prepared by varying the Ag:In ratio from 0% to 8%. The effect of silver concentration on structural and optical properties of In2S3:Ag thin films have been studied in detail using X-ray diffraction (XRD) and ultra violet, visible and near infra red (UV-Vis-NIR) transmittance spectroscopy. The X-ray diffraction analysis showed that the prepared layers are polycrystalline and crystallize in a β-In2S3 cubic structure and the size of the crystallites varies between 16 and 20 nm. UV-Vis-NIR spectroscopy measurements revealed that the optical transmittance of the films exceeds 90% in the visible and near infrared region and also the direct band gap energy of the fabricated thin film samples increases with doping from 2.63 to 2.97 eV. The roughness values evaluated are almost constant for different doping concentration.