Thermoelectric Figure-of-Merit Calculations in Heavily Doped p-Type Lead Telluride

The thermoelectric properties of heavily doped p-PbTe have been studied theoretically in the temperature range from 300 to 900 K. Calculations are based on a three-band model of the PbTe spectrum that takes the transport of electrons and light holes into account in the L-extrema and heavy holes in the Σ-extrema. On the basis of the Boltzmann kinetic equation, a complete set of relevant kinetic characteristics, including the electrical and thermal conductivities, the Seebeck coefficient, and the thermoelectric figure-of-merit ZT has been calculated. All calculated thermoelectric quantities agree well with the available experimental data in the entire temperature interval from 300 to 900 K. The calculation reproduces a significant increase in the thermoelectric figure-of-merit to the value ZT = 1.2 which has been recently detected experimentally in heavily doped p-PbTe samples.