Temperature dependent magnetotransport characterization of Bi_0.88Sb_0.12using two channel analysis

Bi_1-xSb_x alloys with 0.07 < x < 0.22 are narrow-bandgap semiconductors with band inversion resulting in topological insulating properties. These alloys exhibit strong temperature dependent behaviors making them promising thermoelectric materials. Magnetotransport measurements are carried out on Bi_0.88Sb_0.12 in which both L and T bands are present. In the high temperature regime, we follow the assumption where only two types of carriers are present. Using a two-channel analysis on magnetotransport measurements at temperatures between 100K<T<300K allows us to extract carrier densities and mobilities for electrons and holes. Using the extracted values for densities, the band gap is calculated to be 0.057eV in this temperature regime. The electron and hole mobilities increase with decreasing temperature. The electron mobility is fit to the acoustic deformation potential scattering function, however the analysis for hole mobility proves to be more challenging due to the presence of heavy and light holes. In particular, around room temperature the hole mobility is degraded as a result of intervalley scattering from the T and L bands.