Thermoelectric transport in $\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3$ superlattices

TL;DR

This study uses first-principles calculations and Boltzmann theory to analyze thermoelectric transport in Bi2Te3/Sb2Te3 superlattices, revealing doping-dependent anisotropies and quantum confinement effects on transport properties.

Contribution

It provides detailed insights into the anisotropic thermoelectric transport behavior of superlattices under different doping and temperature conditions, highlighting the impact of quantum confinement.

Findings

Hole-doping favors in-plane thermoelectric transport.

Electron-doping causes suppression of cross-plane transport due to quantum confinement.

Transport anisotropies remain bulk-like under hole-doping across all superlattice periods.

Abstract

The thermoelectric transport properties of $\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3$superlattices are analyzed on the basis of first-principles calculations and semi-classical 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 bulk-like 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.