Selective Electrodeposition and Growth Mechanism of Thermoelectric Bismuth-Based Binary and Ternary Thin Films

Abstract

Different morphologies of thermoelectric Bi1-xSbx and Bi2-xSbxTe3 thin films, including rods, dendrites, thin sheets, and spherical particles, were selectively obtained by an electrodeposition method at room temperature (25 °C). Cyclic voltammetry was used for determination of the deposition potentials of thin films. The influences of the deposition potential and the electrolyte composition on the films were studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were employed to characterize the thin films. It was found that the different shaped Bi-rich Bi1—xSbx films can be obtained by tuning the electrolyte composition. However, the Bi2—xSbxTe3 films can be fabricated by changing the deposition potential. In underpotentials (UPD), the reduction reactions of Bi3+, Te4+, and Sb3+ take place to form (Bi0.5Sb0.5)2Te3. When the potential shifts into overpotentials (OPD), Bi0.5Sb1.5Te3 is formed on the electrode surface. The EDS data indicates that the c...