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DS: Fachverband Dünne Schichten

DS 41: Thermoelectric materials III: Heterostructures (Focused session – Organizers: Meyer, Heiliger)

DS 41.5: Talk

Friday, March 30, 2012, 10:30–10:45, H 2032

Thermoelectric Transport in strained Si and Si/Ge heterostructures — Nicki F. Hinsche¹, Ingrid Mertig^1,2, and •Peter Zahn¹ — ¹Martin-Luther-Universität, Institut für Physik, Von-Seckendorff-Platz 1, D-06120 Halle — ²Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle

Starting from bulk silicon, we study the change in thermoelectric properties due to symmetry breaking in strained Si which might be applied in nanostructured thermoelectrics.

In detail, the anisotropy of the electrical conductivity, the thermopower and the resulting power factor in the in-plane and cross-plane directions 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. The electronic structure is calculated self-consistently within the framework of density functional theory. The transport properties are studied in the diffusive limit applying the Boltzmann theory in relaxation time approximation [3].

Furthermore, we present results for strained Si/Ge heterostructures, showing an enhanced power factor in cross-plane direction under electron doping as suggested by Koga et al. [4].

[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, to be published. [3] I. Mertig, Rep. Prog. Phys. 62, 237 (1999). [4] T. Koga, X. Sun, S. B. Cronin, and M. S. Dresselhaus, Appl. Phys. Lett. 75, 2438 (1999).