Effect of polycrystalline structure on the behavior of evaporated β-In2S3 thin films

β-In2S3 thin films were evaporated on 150 °C-heated glass substrates at different sulfur source pressures, showing some change from tetragonal to cubic crystalline structure when the sulfur availability increases. Such structural order remained after post-deposition heating in air at 250 °C and 350 °C, increasing both the crystallite size and the bandgap energy as the heating temperature increased. For a same temperature, the crystallite size is smaller and the energy gap is larger for films grown at higher sulfur pressure. On the other hand, free carrier concentration and electrical conductivity tend to decrease as the heating temperature increases, being the decrease faster for samples grown at lower sulfur pressure. The different behaviors are attributed to differences in structural strain and defects according to growth conditions.