Thermoelectric Characteristics of Heavily Doped p-Type Lead Telluride at Different Heavy-Hole Band Depths

Resumo

The full set of thermoelectric parameters of heavily doped p-PbTe in the temperature range of 300–1200 K at an acceptor doping level of N_a = 1 × 10¹⁹–4 × 10²⁰ cm^–3 and a heavy-hole band depth ranging from 0.36 to 0.7 eV is calculated. The figure-of-merit value Z is found to be highly sensitive to the doping level and increased by a factor of 1.5 with an increase in the dopant concentration from 1 × 10¹⁹ to 5 × 10¹⁹ cm^–3; the maximum Z value is found to correspond to N_a = (1–2) × 10²⁰ cm^–3. It is demonstrated that the change in the heavy-hole band depth leads to a noticeable shift of the Z maximum position along the temperature axis without noticeable Z maximum variation. The temperature corresponding to the maximum Z value is similar to that at which the top of the light-hole band crosses the Fermi level. The maximum calculateded ZT value is shown to be 1.64. At a heavy-hole band depth of 0.5 eV, the calculated results agree well with the available experimental data.