High doping effect on the thermoelectric properties of p-type lead telluride

摘要

We study theoretically the effect of heavy doping on the thermoelectric properties of p-type PbTe in the acceptor doping interval of 5 x 10(19) to 4 x 10(20) cm(-3) and in the temperature range of 300 to 900K. In our calculations, a three-band model of the PbTe electron energy spectrum is used that takes into account not only the light electron and hole bands but also the heavy-hole band. This so-called R-band plays an important role in the emergence of the figure-of-merit increase in this material at heavy acceptor doping. The calculated thermoelectric characteristics appear to be sensitive to the doping level. An increase in the figure-of-merit up to ZT approximate to 1.3 at 900K was found at the doping level of 2 x 10(20) cm(-3). The maximum of ZT on the temperature axis is situated close to the temperature at which the light hole and heavy hole band edges coincide and hence, a prominent density-of-states singularity appears in the valence band, and the Fermi level lies near this singularity. Published by AIP Publishing.