Electronic thermal conductivity and thermoelectric figure of merit of n-type PbTe/Pb1-xEuxTe quantum wells

We have investigated the electronic thermal conductivity and thermoelectric figure of merit of (100) and (111) oriented PbTe/Pb1-xEuxTe quantum wells. Our theoretical formalism includes the nonparabolicity of the carrier dispersion, band anisotropy, as well as carrier scattering on acoustic and optical phonons and presents a substantial improvement over existing models. The kinetic equations are solved by iterations taking into account multisubband transitions. The values of the electronic thermal conductivity and thermoelectric figure of merit are examined in a wide range of the quantum well widths and carrier concentrations. It is found that in (111) oriented quantum wells the electronic thermal conductivity and Lorentz number are strongly enhanced due to the lifting of the valley degeneracy. The effect of the confined carrier-phonon scattering on the value of the thermoelectric figure of merit is analyzed in detail. The obtained results are in good agreement with available experimental data for thin quantum wells and bulk material. The developed formalism can be used for accurate simulation of the thermoelectric properties of low-dimensional structures.