Effect of annealing on In2S3 thin films prepared by flash evaporation

In 2 S 3 thin films were deposited by flash evaporation of In 2 S 3 powder. The effect of annealing in vacuum and under sulphur and oxygen atmosphere on the structural, compositional and optical properties of these films was investigated. X-ray diffraction studies reveal that the as-deposited films are amorphous. The formation of β -In 2 S 3 phase is obtained after annealing under vacuum at 693 K or under sulphur pressure at a lower annealing temperature (573 K). The EDAX analysis reveals that the sulphurized films are nearly stoichiometric and those annealed in vacuum are sulphur deficient. Optical transmission spectra showed a slight shift of the absorption edge towards lower wavelengths. The optical gap value varied between 2.4 and 3 eV as a function of the film thickness, the annealing temperature and the atmosphere ambient.