Experimental studies and new theoretical modeling on the properties of In2S3 thin films

Abstract

Indium sulfide (In2S3) is a material extensively used as an alternative buffer layer to that of cadmium sulphide (CdS) for thin film photovoltaic applications. In this work, In2S3 thin films were obtained over SiO2 glass with various substrate temperatures (Ts) using the vacuum thermal evaporation method. The effect of Ts which varies from 25 °C to 300 °C on structural, optical and morphological homestead are reported and discussed here. Our deposited In2S3 films are typified via X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and UV–Vis–NIR spectroscopy. XRD analysis reveals the amorphous nature of all samples. AFM graphics reveals that the deposited layers are smooth along relatively high surface roughness. The UV–Vis–NIR spectra show a high transmittance for all samples ranging from 75% to 90%, over the region extending from the UV–Vis to the near-infrared. The evaluated optical band gap energy showed a decrease from 2.60 eV to 2.12 eV with increasing Ts, which might be attributed to the presence of high concentration of defects, in the compound band structure. These experimental data were confirmed by theoretical predictions obtained by transfer matrix method (TMM) simulations.