Thermoelectric transport in Bi sub(2)Te sub(3)/Sb sub(2 )Te sub(3) superlattices

The thermoelectric transport properties of Bi sub(2)Te sub(3)/Sb sub(2 )Te sub(3) superlattices are analyzed by means of first-principles calculations and semiclassical Boltzmann theory. The anisotropy of the thermoelectric transport under electron and hole doping was studied in detail for different superlattice periods at changing temperature and charge carrier concentrations. A clear preference for thermoelectric transport under hole doping, as well as for the in-plane transport direction was found for all superlattice periods. At hole doping the electrical transport anisotropies remain bulklike for all investigated systems, while under electron doping quantum confinement leads to strong suppression of the cross-plane thermoelectric transport at several superlattice periods. In addition, insights on the Lorenz function, the electronic contribution to the thermal conductivity, and the resulting figure of merit are given.