Electrochemical Impedance Spectroscopic Study of Electrodeposited Bi2Te3-based Thin Films

Abstract

The Bi2Te3-based thin films have been prepared by electrochemical deposition on stainless-steel substrates. The microstructure and composition of the films were studied by X-ray diffraction (XRD) and electron probe microanalysis (EPMA). The deposition mechanisms of Bi2Te3 thin films on stainless-steel substrates were preliminary investigated using electrochemical impedance spectroscopy (EIS). The results showed that the similar deposition mechanisms were obtained for Bi-Te binary and Bi-Te-Se ternary systems, i.e., the Bi3+, HTeO2+ and H2SeO3 were electrochemically reduced to form simple substances Bi(0), Te(0) and Se(0), respectively, then the Bi2Te3-based compounds were formed by reacting Te(0) or Se(0) with Bi(0). For Bi-Sb-Te ternary system, the HTeO2+ was first electrochemically reduced to form simple substance Te(0), and then the Bi2Te3-based compounds were formed by reacting Te(0) with Bi3+ and Sb(III). The deposition processes were controlled by electrochemical polarization.