Formation and properties of copper chalcogenides thin films on polymers formed using sodium telluropentathionate

Abstract

The preparative conditions were optimized to get chalcogens layers on the polymer — polyamide PA surface by sorption at room temperature using sodium telluropentathionate, Na₂TeS₄O₆. Further interaction of chalcogenized dielectric with copper’s (I/II) salt solution leads to the formation of mixed Cu_xS_y-Cu_xTe_y layers. Optical, electrical and surface characteristics of the layers are highly controlled by the deposition parameters. The stoichiometry of these layers was established by UV-Visible and AA spectrometry. Optical absorption (transmittance) experiments show the samples are of high optical quality. The band gaps of thin films were obtained from their optical absorption spectra, which were found in the range of 1.44–2.97 eV. XRD was used in combination with AFM to characterize chalcogenides layers’ structural features. XRD analysis confirmed the formation of mixed copper chalcogenides’ layers in the surface of PA with binary phases such as Cu₂Te, Cu_3.18Te₂, copper telluride, Cu_2.72Te₂, vulcanite, CuTe, anilite, Cu₇S₄ and copper sulfide, Cu_1.8S. The crystallite sizes of thin films calculated by the Scherer formula were found to be in the range of 3.07–13.53 nm for Cu_xS_y crystallites and 4.06–20.79 nm for Cu_xTe_y crystallites. At room temperature an electrical resistance of Cu_xS_y-Cu_xTe_y layers varies from 3.0×10³ kΩ□⁻¹ to 1.0 kΩ□⁻¹.