Fabrication and some physical properties of AgIn5S8 thin films

AgIn5S8 thin films are deposited on glass substrates, kept at 300 K, by thermal evaporation of AgIn5S8 single crystals under the pressure of 10–5 Torr. The X-ray fluorescence analysis revealed that the films have a weight percentage of ∼11.5% Ag, 61.17% In, and 27.33% S which corresponds to 1:5:8 stoichiometric composition. X-ray analysis of the films reveals the polycrystalline nature of the films. The lattice parameter (a) of the films was calculated to be 10.784(5) Å. The dark n-type electrical conductivity of the films was measured in the temperature range of 30–350 K. The conductivity data analysis shows that the thermionic emission of the charge carriers having activation energies of 147 and 224 meV in the temperature ranges of 130–230 and 240–350 K, respectively, are the dominant transport mechanism in the films. The variable range hopping transport mechanism is dominant below 130 K. The room temperature photocurrent–photon energy dependency predicts a band gap of 1.91 eV of the films. The illumination intensity-photocurrent dependency measured in the intensity range of 13–235 W cm−2 reveals monomolecular recombination (linear) in the films and bimolecular recombination (sublinear) at the film surface corresponding to low and high applied illumination intensities, respectively. The time-dependant photocurrent measured at fixed illumination intensity reveals a response time of 0.85, 2.66 and 10.0 s in the time periods of 0–0.5, 0.5–1.0, and 1.0–10.0 s, respectively.