A method for analysis of carrier density and mobility in polycrystalline bismuth

Carrier densities and mobilities in polycrystalline bismuth contaminated with 0.01 at% tin are determined by measurement of various electronic transport parameters in low magnetic fields from 50 to 300 K. The parameters measured include the Seebeck coefficient, resistivity, magneto-resistance and Hall coefficient. The present sample exhibits the temperature-dependent variations in electron carrier density seen for single-crystal bismuth. However, due to tin contamination of 0.01 at%, the hole carrier density is invariant below 150 K. The mobilities are somewhat lower due to boundary scattering, with the reduction in electron mobility being prominent. The proposed method allows the temperature dependences to be determined reliably even in the presence of contamination, and represents a useful technique for the analysis of carrier densities and mobilities in high-mobility materials under low magnetic fields.