Synthesis and properties of In-2(Se1-xTex)(3) thin films: a new semiconductor compound

In-2(Se1-xTex)(3) polycrystalline films were prepared by a dual-source ther mal evaporation technique. The depositions onto glass and SnO2-coated glass substrates were carried out in a vacuum chamber and followed by an anneali ng in neutral ambient (Ar or N-2) The structural, morphological and composi tional studies of the films were made by X-ray diffraction, energy-dispersi ve X-ray analysis, X-ray photoelectron spectroscopy, scanning electron micr oscopy, Raman scattering and optical transmission. Optimum conditions are i nvestigated for the formation of the ternary compound In-2(Se1-xTex)(3) in order to tune the band gap by changing the Te concentration. The film prope rties as a function of Te amount are discussed. It is shown that single-pha se, textured and homogeneous layers of In-2(Se1-xTex)(3) can be grown with x less than or equal to 0.2 at optimal deposition and heat treatment condit ions. For x congruent to 0.17 these films showed an energy band gap of abou t 1.45 eV and an electrical conductivity at room temperature six orders of magnitude higher than that of the binary gamma -In2Se3 thin films.