Electrochemical and structural investigation of BixTey thin films electrodeposited on ITO substrate

• Published in: Applied surface science advances 2023-08, Vol.16, p.100419, Article 100419
• Main Authors: Youbi, Boubaker, Lghazi, Youssef, Ait Himi, Mohammed, Aynaou, Aziz, Bahar, Jihane, El Haimer, Chaimaa, Ouedrhiri, Abdessamad, Sahlaoui, Ahmed, Bimaghra, Itto
• Format: Article
• Language: English
• Subjects: Bismuth telluride; Chronoamperometry; Electrodeposition; Nucleation; Stoichiometry
• ISSN: 2666-5239; 2666-5239
• DOI: 10.1016/j.apsadv.2023.100419

•BixTey electrodeposition on ITO substrate from nitric acid solution is a quasireversible reaction controlled by the diffusion process.•The composition of the electrolyte in Bi3+ and HTeO2+ allows for the stoichiometric control of the electrodeposited BixTey compound.•The BixTey electrodeposition mechanism follows a progressive 3D nucleation for low Bi3+ concentrations and a 3D instantaneous nucleation for higher concentrations. Bismuth telluride films with various stoichiometries BixTey have been successfully elaborated by potentiostatic deposition on indium tin oxide (ITO) substrate from an acidic solution containing a mixture of different concentrations of Bi3+ and HTeO2+ ions. The electrochemical study using cyclic voltammetry and chronoamperometry shows that the electrodeposition of bismuth telluride is a quasi-reversible reaction controlled by the diffusion process and the composition of the reaction mixture controls the BixTey stoichiometry. It was found, from electrochemical and EDS analysis, that a mixture in stoichiometric proportions leads to the formation of bismuth tellurium Bi2Te3, an excess of telluryl ion HTeO2+ gives a product rich in tellurium Bi2-xTe3+x, but a high concentration of Bi3+ (compared to the stoichiometry) gives rise to the electrodeposition of a compound rich in bismuth Bi2+xTe3-x. The chronoamperometric analysis of current density-time transients using Scharifker-Hills model showed that the mechanism of deposition and growth of BixTey on ITO substrate takes place according to a progressive 3D nucleation for low Bi3+ concentration and 3D instantaneous nucleation for higher concentration. The morphology of the BixTey films is strongly depending to the electrolytes composition. The X-ray diffraction characterization shows that the crystalline structure of bismuth tellurium BixTey produced is of the rhombohedral type. [Display omitted]