Preparation and characterization of In4Se3 films

Thin films of In4Se3 were obtained by vacuum evaporation of polycrystalline materials onto substrates at different temperatures Ts. Systematic X-ray analysis was carried out and revealed that the flash evaporation technique can produce stoichiometric films for depositing polycrystalline materials of composition In1.11Se0.89. Optical and electrical characterizations are reported. The energy gap of In4Se3 films is located between 1.41 and 1.48 eV depending on the substrate temperature. A.c. and d.c. conductivities were measured as a function of Ts. Amorphous films exhibit a T−14 dependence of the conductivity which fits well with the Mott model with a density of localized states N(EF) = 8.5 × 1018cm−3eV−1. The effect of annealing temperature was also investigated. Hall measurement as a function of temperature show that the predominant conduction mechanism is scattering by grain boundaries in polycrystalline In4Se3 films.