Properties of photoconductive In Se thin films, crystallized by 2 3 post-deposition heat treatment in nitrogen atmosphere

Textured thin films of g-In2Se3 were grown on glass substrates by sequential thermal evaporation of In and Se. The crystallization was achieved by annealing the as-deposited films in flowing nitrogen. It is shown by X-ray diffraction XRD. measurements that single phase g-In2Se3films are obtained by annealing half an hour at 673 K. The films obtained on bare glass substrates and on SnO2 coated glass substrates are textured along the 001.direction while those obtained on mica sheet and gold coated glass are not. The films are stoichiometric. Films deposited on glass substrates have been optically characterized. At room temperature, the measured band gap is 1.8 eV. In the case of thick films 1 mm., the surface of the films becomes rough, which can explain the higher photoconductivity of the films when the light beam is incident upon the substrate. Effectively, at the interface glassrfilm there is not any rugosity and the trap density is smaller than at the interface film surfacerair. Photoluminescence spectra are obtained in the temperature range 78–200 K. Two peaks are observed. The width and the energy position of the main peak are temperature dependent. It is situated in the gap energy range and can be attributed to exciton recombination, while the other small one can be attributed to some intrinsic defects. q1999 Elsevier Science B.V. All rights reserved.