Microstructure and thermoelectric properties of p-type Bi–Sb–Te–Se thin films prepared by electrodeposition method

Abstract

P-type Bi–Sb–Te–Se thermoelectric thin films with thickness of 8μm have been prepared by cathodic electrodeposition technique on Au substrate from nitric acid solution system at room temperature. Cyclic voltammetry was used for determination of the deposition potentials of the thin films. In order to enhance the crystallinity, as well as the thermoelectric properties of the deposited films, they were annealed at 523K for 2h under nitrogen atmospheric pressure condition. X-ray diffraction (XRD), environmental scanning electron microscopy, and energy-dispersive spectroscopy (EDS) were employed to characterize the thin films. Seebeck coefficients and resistivities of the films were also evaluated. The results revealed that Bi, Sb, Te and Se could be co-deposited to form Bi–Sb–Te–Se semiconductor compound in the solution containing BiIII, SbIII, TeIV and SeIV and the compositions of the films were sensitive to the electrodepositing potentials. The XRD results suggested that the crystal structure of the thin films were changed from amorphous state to polycrystalline after annealing. The EDS data indicated that the composition of the films was consistent with XRD results. The annealed Bi–Sb–Te–Se thin films exhibited the Seebeck coefficients of 116–133μV/K and a maximum power factor of 0.62mW·K−2·m−1.