Theoretical comparison of electronic and lattice thermal conductivities in n-type (Bi_1-xSb_x)₂Te₃ solid solutions

We have theoretically investigated the electronic and lattice thermal conductivities for various carrier concentrations in the n-type (Bi_1-xSb_x)₂Te₃ solid solutions using the two-band conduction model with a mixed scattering mechanism. For operation of thermoelectric cooling at low temperatures, the carrier concentration must be controlled so that the electronic thermal conductivity makes the total thermal conductivity have the minimum at an applicable temperature. Under this condition, the electronic thermal conductivity is over 25% of the lattice thermal conductivity and results in the gradual increase of the thermal conductivity. These effects are almost independent of the composition x under the same carrier concentration.