Physical Properties and Ethanol Response of Sprayed In2S3:Sn Films

Abstract

AbstractIn this study, tin-doped indium sulfide thin films (In2S3:Sn) at different molar ratios of Sn:In (0–1% by mol in solution) were deposited on glass substrates by chemical spray pyrolysis method. The films were investigated by X-ray diffraction, optical absorption , Raman and photoluminescence spectroscopies, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The structural properties reveal that the In2S3:Sn thin films have a polycrystalline cubic structure and the average crystallite size increases from 16.3 to 25.5 nm. The surface morphology of the films is continuous and free of cracks. The average surface roughness and the root-mean square roughness increase from 13.12 to 31.65 nm and from 16.14 to 39.39 nm, respectively, with increasing of Sn:In molar ratio. Raman studies reveal the presence of modes of vibrations related to In2S3 phase, with no signature of secondary phases. The transmission coefficient is about 65–70% in the visible region and 70–90% in near-infrared region . The optical band gap values of In2S3:Sn for allowing direct transitions were found to be in the range 2.68–2.80 eV. The refractive index of In2S3:Sn thin films has decreased from 2.45 to 2.37 and the k values are in the range 0.02–0.25 for all wavelengths. Defects-related photoluminescence properties were also discussed. Effect of tin doping on ethanol sensing response was also investigated. A slight enhancement in response is shown for In2S3:1%Sn sample.KeywordsSn-doped In2S3Spray pyrolysisStructural propertiesRaman and photoluminescence spectroscopyOptical propertiesEthanol sensing