Seebeck coefficient of p-type PbTe/PbEuTe quantum well structures

The electrical conductivity σ and Seebeck coefficient S are calculated in [111] oriented p-type PbTe/PbEuTe quantum well (QW) structures using the iterative method for solving the kinetic equations. The carrier scattering by optical and acoustical phonons is considered. The dependencies of σ and S vs. well width d and hole concentration p are studied. It is shown that for small d=20Å the energy gap between oblique L and Σ valleys becomes small and the Seebeck coefficient achieves large values even at very high carrier concentration of p∼10²⁰ cm^-3. The presence of high mobility degenerate holes in the longitudinal subbands L valley leads to a small decrease of S. The obtained values of the conductivity and thermoelectric power agree well with the experimental data in the concentration range of p<10²⁰ cm^-3.