Electrodeposition of silver telluride thin films from non-aqueous baths

We describe a method for preparation of crystalline silver telluride films by cathodic deposition from dimethyl sulfoxide (DMSO) solutions containing 0.1 M NaNO₃, 5.0 mM AgNO₃ and 3.5-7.0 mM TeCl₄. X-ray diffraction data indicated that the deposited silver telluride films could be adjusted from Ag excess and stoichiometric monoclinic Ag₂Te to hexagonal Ag₇Te₄ by increasing the concentration of TeCl₄ in the electrolyte or lowering the deposition potential. The Ag₂Te film is gray and the Ag₇Te₄ film is dark blue-gray and mirror like adhered strongly to the substrates. Scanning electron microscopy images show that Ag₂Te films were formed with globular grains with average diameters of more than 1 μm. In contrast, Ag₇Te₄ film consists of triangles characteristic of a (1 1 1) single-crystal with a hexagonal structure in average sizes of about 0.4 μm. The X-ray photoelectron spectra (XPS) indicated that the binding energies deviation of Te3d in Ag₇Te₄ is less than that in Ag₂Te, which is consistent with the apparent valences of Te in Ag₂Te and Ag₇Te₄. Finally, the cathodic deposition reactions were studied by cyclic voltammetry.