Growth mechanism during the early stages of electrodeposition of bismuth telluride Bi2Te3 on ITO substrate

Abstract

The electrochemical deposition mechanism of Bismuth telluride (Bi2Te3) by co-reduction of the telluryl (HTeO2+) and bismuth ions from the nitric acid medium on tin doped indium oxide (ITO) substrate was investigated using two electrochemical techniques: cyclic voltammetry (at different scan rates) and chronoamperometry (at different applied potentials). The thin films electrodeposited by chronoamperometry were characterized by X-Ray diffraction (XRD) and UV–Visible spectroscopy, the exploitation of UV–visible curves allowed us to calculate the gap energy. Surface morphology was examined using a scanning electron microscope (SEM) and atomic force microscope (AFM). These techniques have shown that the electrodeposition of Bi2Te3 has been performed at a negative potential around −0.18 V vs SCE, with a quasi-reversible reaction controlled by the diffusion process. Moreover, the measured current transient curves were compared to those calculated from Scharifker-Hills models. It was found that a progressive 3D nucleation mechanism governs the nucleation and growth of Bi2Te3 on ITO substrate.