Growth and characterization of polycrystalline InSe thin films

Indium selenide films were obtained by the thermal evaporation of undoped crystals at substrate temperatures of 210 and 300 IC. Films were found to exhibit n-type conductivity. Scanning electron microscopy established that the films grown on glass substrates held at 210 degrees C had an atomic content of In46.66Se53.34, whereas the films obtained under the same conditions and annealed in vacuum at 150 degrees C had an atomic content of In48.13Se51.87. X-Ray diffraction indicated that the films were polycrystalline in nature and crystallized in the D-3h(1) space group. From an analysis of Hall and conductivity measurements, performed in the temperature ranges 110-320 K and 10-320 K respectively, thermionic emission is considered to be the predominant transport mechanism above 200 K. The current transport below 75 K is due to the hopping of carriers between localized states. In the intermediate temperature region, both thermally assisted tunnelling and thermionic emission contribute to the conduction