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Indium sulfide (In2S3) films with three different thicknesses (150, 400 and 600 nm) were prepared using thermal evaporation at room temperature. As prepared samples were amorphous and subsequent annealing at higher temperature (>573 K) resulted in the formation of crystalline phase. Optical band gap was found in the range of 1.9–2.9 eV for as prepared samples and decreased with increase in annealing temperature. Interference fringe like structure in transmission spectra revealed that the films were fairly smooth and reflective. Variations in electrical resistivity and photosensitivity as a function of film thickness and annealing temperature were studied. X-ray Photoelectron Spectroscopic (XPS) studies clearly indicated uniform distribution of both indium and sulphur along the film. Energy Dispersive X-ray analysis showed that as prepared samples were stoichiometric. [ABSTRACT FROM AUTHOR]

Thermally Stimulated Conductivity (TSC) has been used to analyse defects in the novel material ß -In2S3. These films were deposited using spray pyrolysis technique, varying In:Sconcentration ratio in the spraying solution. TSC measurements allowed the study of electrical property and non-radiative transitions, due to the defects present in the material. TSC spectra revealed four defects with their prominence varying with In:Sconcentration ratio. Samples with lower In concentration showed the presence and prominence of indium vacancy. A chemical impurity level due to the presence of chlorine was also detected. Even though sulphur vacancy existed in all the samples irrespective of the variation of In:Sconcentration ratio its effect decreased with the increase of sulphur concentration. Another defect level was also detected from TSC measurements at high temperature that was attributed to the replacement of sulphur by oxygen which was maximum in films prepared from a spray solution of In:S= 2:3 and minimum for 2:8. This high temperature defect level acts as a neutral center while all the other three levels were seen to be coulomb repulsive. Results from XPS analysis are found to be in good agreement with the TSC results. [ABSTRACT FROM AUTHOR]