Regensburg 2010 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 13: Thermoelectric Thin Films and Nanostructures I

DS 13.10: Vortrag

Dienstag, 23. März 2010, 12:45–13:00, H8

Strained and rolled up silicon: Electronic structure calculations of a promising thermoelectric material — •Nicki Hinsche, Bogdan Yavorski, Peter Zahn, and Ingrid Mertig — Martin-Luther-Universität, Institut für Physik, Von-Seckendorff-Platz 1, 06120 Halle/S.

Starting from bulk silicon, we studied the valley splitting due to symmetry breaking that occurs in rolled-up Si. Valley splitting in Si was studied recently because of tetragonal distortion and quantum well effects in heterostructures [1,2]. The new aspect in nowadays experimentally accessible rolled-up Si tubes is that symmetry breaking occurs in all spatial directions [3]. As a result, splitting of the six-fold degenerate conduction-band minimum is expected to be lifted. This has a strong influence on the transport properties as well. In detail, the anisotropy of the effective masses of charge carriers contributing to the conductivity in different directions will be studied in dependence on the applied strain. The electronic structure is calculated self consistently within the framework of density functional theory. The transport properties of the promising thermoelectric material will be studied in the diffusive limit of transport applying the Boltzmann theory in relaxation time approximation.

[1] Dziekan et al. Physical Review B 75, 195213 (2007) [2] Boykin et al. Physical Review B 70, 165325 (2004) [3] Cavallo et al. Journal of applied physics 103, 116103 (2008)