Calculation of the Thermoelectric Characteristics of Lead Telluride at a High Level of Acceptor Doping

Abstract

The thermoelectric properties of p-РbТе were studied theoretically at the level of acceptor doping within 5 × 10¹⁹ to 4 × 10²⁰ cm^–3 and in the 300–900 K temperature range. The three-band model of the electron energy spectrum of PbTe that was used in the calculations includes not only the bands of light electrons and holes in L-points of Brillouin zone but also the band of heavy holes in its Σ-points. The heavy Σ-band plays an important role in increasing the thermoelectric figure of merit of this material at high levels of acceptor doping. The calculated values of thermoelectric characteristics are very sensitive to the doping level. The calculations revealed that thermoelectric figure of merit increases with the doping level up to ZT ≈ 1.3 at 900 К. This maximum is located near the temperature at which the peaks of the bands of light and heavy holes coincide in energy and sharp singularity of density of states arises in the valence band; the Fermi energy is not far from the singularity.