The underpotential deposition of Bi2Te3-ySey thin films by an electrochemical co-deposition method

Bi2Te3-7Sey thin films were grown on Au(1 1 1) substrates using an electrochemical co-deposition method at 25 degrees C. The appropriate co-deposition potentials based on the underpotential deposition (upd) potentials of Bi, Te and Se have been determined by the cyclic voltammetric studies. The films were grown from an electrolyte of 2.5 mM Bi(NO3)(3), 2 mM TeO2, and 0.3 mM SeO2 in 0.1 M HNO3 at a potential of -0.02 V vs. Ag/AgCl (3 M NaCl). X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were employed to characterize the thin films. XRD and EDS results revealed that the films are single phase with approximate composition of Bi2Te2.7Se0.3. SEM studies showed that the films are homogeneous and have micronsized granular crystallites. (C) 2008 Elsevier Ltd. All rights reserved.