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 mum. 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 mum. 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. (C) 2004 Elsevier Ltd. All rights reserved.