Thermoelectric properties of PbTe films and PbTe-based superlattices

Abstract

The electrical conductivity, Seebeck coefficient, and thermoelectric conversion efficiency of n- and p-type PbTe were calculated over the temperature range of 300-800K by using Boltzmann transport theory and relaxation time approximation, and they were compared with experimental results. A three band model for PbTe was used and alloy scattering from donor or acceptor impurities was included to explain a low electrical mobility at high carrier concentration region exceed 1×1019 cm-3 as well as scatterings from the deformation potential of the acoustic and optical phonons, screened polar optical phonon, and ionized impurity. Nonparabolicity and anisotropy of the L-point valleys were took into account in the calculation. The nonparabolicity and resultant enhancement of the effective masses resulted in the large temperature dependence of conductivity in n-type PbTe. A large Seebeck coefficient in highly p-type PbTe was explained by heavy effective masses in Σ valleys, and carrier mobility of the heavily doped sample was simulated by assuming large deformation potentials for Bi donor and Tl, Na, and K acceptor impurities. Electrical conductivity, Seebeck coefficients and power factors for EuTe/PbTe superlattice and GeS/PbTe amorphous / epitaxial superlattice were also presented and discussed here.