Numerical Analysis of Thermoelectric Properties of Bi₈₈Sb₁₂ by the Multi Carrier Model

Abstract

  The large thermopower maximum observed for the bismuth antimony (Bi₈₈Sb₁₂) alloy as a function of temperature, is studied based on the multi-carrier model using the Boltzmann transport theory and Fermi integration. The chemical potential of this system has been initially calculated at each temperature from the observed Hall coefficient data. It was observed that the calculated chemical potential remains close to the bottom of the conduction band at low temperatures, and then increases at T=70 K, where the thermopower maximum is observed. The calculation also showed a similar maximum at this temperature. From the calculated results, the temperature dependence of the thermopower is associated with the transition between extrinsic conduction and intrinsic conduction, and thus the Bi₈₈Sb₁₂ alloy is recognized as a strongly degenerate semiconductor.