Insights into the Electrodeposition of Bi2Te3

Abstract

In this paper, the processes associated with the electrodeposition of bismuth telluride (Bi2Te3), a thermoelectric material, are reported along with an analysis of the composition and crystallinity of the resulting films. The electrodeposition can be described by the general reaction 3HTeO2+ + 2Bi3+ + 18e– + 9H - Bi2Te3 + 6H2O. Cyclic voltammetry studies of Bi, Te, and Bi/Te dissolved in 1 M HNO3 reveal two different underlying processes depending on the deposition potential. One process involves the reduction of HTeO2+ to Te0 and a subsequent interaction between reduced Te0 and Bi3+ to form Bi2Te3. A second process at more negative reduction potentials involves reduction of HTeO2+ to H2Te followed by the chemical interaction with Bi3+. Both processes result in the production of crystalline Bi2Te3 films in the potential range –0.1<E<–0.52 V vs. Ag/AgCl (3 M NaCl) on Pt substrates as determined by powder X-ray diffraction (XRD). Electron probe microanalyses and XRD reveal that the films are bismuth-rich and less oriented for more negative deposition potentials.