Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

The thermoelectric transport properties of layered structures are analyzed by means of first-principles calculations and semi-classical Boltzmann theory. The electronic structure of the systems was calculated by means of a fully relativistic screened Korringa-Kohn-Rostoker Greens function method. The transport properties along in-plane and cross-plane direction were obtained within the relaxation time approximation of the Boltzmann theory.
We studied the change in thermoelectric properties due to symmetry breaking in Si and Si/Ge heterostructures. The anisotropy of the electrical conductivity, the thermopower and the resulting power factor are studied in dependence on doping level, temperature, and strain in [001] and [111] direction. Our results show that tetragonal [1] and rhombohedral [2] distortions have a strong influence on the thermoelectric transport properties.
Furthermore, we investigated the influence of strain and lattice period in Bi2Te3/Sb2Te3-heterostructures which show a remarkable enhancement of the thermoelectric figure of merit compared to the bulk materials [3]. To identify the physical origin, we studied the influence of composition, interfacial strain, and doping in detail. In addition, insights on the Lorenz function, the electronic contribution to the thermal conductivity, and the resulting figure of merit are given [4,5].

References

[1] N. F. Hinsche, I. Mertig, and P. Zahn, J. Phys.: Cond. Matt. 23, 295502 (2011)
[2] N. F. Hinsche, I. Mertig, and P. Zahn, Thermoelectric transport in strained Si and Si/Ge heterostructures, J. Phys.: Cond. Mat. 24, 275501 (2012)
[3] R. Venkatasubramanian, E. Siivola, T. Colpitts, and B. O’Quinn, Nature 413, 597 (2001)
[4] N. F. Hinsche, B. Yu. Yavorsky, M. Gradhand, M. Czerner, M. Winkler, J. König, H. Böttner, I. Mertig, and P. Zahn, Thermoelectric transport in Bi2Te3/Sb2Te3 superlattices, Phys. Rev. B 86, 085323 (2012)
[5] N. F. Hinsche, I. Mertig, and P. Zahn, Lorenz function of Bi2Te3/Sb2Te3 superlattices, J. Electronic Materials, 10.1007/s11664-012-2279-z (DOI) (2012)