Thermoelectric transport in multivalley PbTe/PbEuTe quantum wells

The thermoelectric properties of PbTe/PbEuTe quantum wells are investigated theoretically employing a more realistic well model than it was used up to now. The carrier scattering both on optical and acoustical phonons is considered. The electrical conductivity and Seebeck coefficient are calculated using the variational method taking into account the intersubband scattering. It is found that for decreasing well widths, the electrical conductivity decreases for [100] oriented structures, and increases for [111] ones. The thermopower is higher in [100] oriented structures than in [111] ones, especially for very thin wells. The power factor is also higher in [100] wells, but the more realistic is the well model the lower is the value of power factor. So, when the dependence of effective mass on well width is taken into account, the power factor for very thin wells decreases by 14% in [100] oriented quantum wells, and by 12% in [111] ones. The power factor is calculated as a function of carrier concentration and the optimal concentrations are determined for quantum wells of different heights. The results of recent experiments are discussed.