The influence of the substitution of Te for Se on the photoconductive properties of In2Se3-xTe3xthin films

Thin films of In 2 Se 3-3 x Te 3 x compounds have been synthesized by annealing, in constant argon flow, a multilayer structure of indium, selenium and tellurium, sequentially deposited. The films have been characterized by x-ray diffraction (XRD), electron microprobe analysis and x-ray photoelectron spectroscopy (XPS) measurements. These studies have shown that the thin films after annealing are stoichiometric with In at.%/(Se + Te) at.% = 2/3. Qualitative XPS analyses have provided evidence that the surface of the films is chalcogen deficient. XRD measurements have shown that the thin films are crystallized in the hexagonal structure of γ-In 2 Se 3 . The transmission curves obtained by optical measurements show that the absorption threshold is about 1.8 eV when x varies between 0 and 0.25. The photoconductivity measurements have shown that the presence of some at.% of Te (0.8 at.%-8 at.%) improves the photocurrent of the films. The photocurrent is increased by more than five orders of magnitude in the presence of 8 at.% of Te. These properties make In 2 Se 3-3 x Te 3 x compounds very interesting materials as regards use as absorbers in thin-film solar cells.