Electrodeposition conditions-dependent crystal structure, morphology and electronic properties of Bi films

Abstract

The study is devoted to the electronic properties and structure of bismuth films obtained by electrodeposition from high-speed perchlorate electrolyte. Polycrystalline samples were synthesized in acidic perchlorate electrolyte under the (0.18–70.0) mA/cm2 cathode current density and annealed at 265 °C in the He gas atmosphere. The structure, microstructure and electron properties of Bi films were characterized using X-Ray diffraction analysis, scanning electron microscopy, and electron backscattered diffraction. Electrical resistance, magnetoresistance, and Hall coefficient were studied at the 5–300 K temperature range under magnetic field up to 8 T. A specific and unexpected behavior has been found concerning the average size and shape of Bi grains with increasing of the current density: the increase in deposition current density up to 70.0 mA/cm2 contributes to Bi films formation with more isotropic and reduced average grains size. Samples synthesized under 0.18 mA/cm2 current density after annealing showed electronic properties, including magnetoresistance, similar to those of flawless single-crystals. The differences in the electronic characteristics of Bi films electrodeposited under different currents and electrolyte composition were explained by changes in electronic mobility due to scattering on grain boundaries.