Temperature dependence of carrier scattering in polycrystalline bismuth

The dependence of the scattering process on temperatures ranging from 50 to 300 K was comprehensively investigated by measuring five transport coefficients (resistivity, magnetoresistivity, Seebeck coefficient, Hall coefficient, and Nernst coefficient) using polycrystalline bulk bismuth. The values of five physical properties (carrier density, electron and hole mobilities, and electron and hole Fermi energies) were calculated assuming that carrier scattering ranged from acoustic deformation potential scattering to ionized impurity scattering. The accompanying mean-free paths of carriers were also evaluated using the calculated Fermi energy and the effective mass tensor. The mean-free path and grain size (typically several micrometers) obtained from electron backscattered diffraction helped narrow the distribution range of the different scattering processes. Thus, the physical properties, including temperature dependence of the scattering processes, were recalculated, and realistic temperature dependence of the electron mobility was assumed. Quantitative and qualitative analyses showed that near room temperature, acoustic deformation potential scattering dominated, which changed to ionized impurity scattering when the estimated mean-free path exceeded 1 mu m. This indicated that the scattering process of polycrystalline bulk bismuth depends on the grain size when the measurement results of the Nernst coefficient related to the scattering process are directly used. The bandgap energy of bismuth was also calculated, and the temperature dependence of the scattering process was estimated. The results showed that the temperature dependence tendency of bandgap energy is similar to that described in the literature. Finally, this study provides the temperature dependence of the physical properties of polycrystalline bismuth. Published under license by AIP Publishing.