Insights into the Electrodeposition of Bi[sub 2]Te[sub 3]

Abstract

In this paper, the processes associated with the electrodeposition of bismuth telluride (Bi 2 Te 3 ), 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 3HTeO 2 2Bi 3 18e 9H Bi 2 Te 3 6H 2 O. Cyclic voltammetry studies of Bi, Te, and Bi/Te dissolved in 1 M HNO 3 reveal two different underlying processes depending on the deposition potential. One process involves the reduction of HTeO 2 to Te 0 and a subsequent interaction between reduced Te 0 and Bi 3 to form Bi 2 Te 3 . A second process at more negative reduction potentials involves reduction of HTeO 2 to H 2 Te followed by the chemical interaction with Bi 3 . Both processes result in the production of crystalline Bi 2 Te 3 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.