Dresden 2011 – scientific programme

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DS: Fachverband Dünne Schichten

DS 59: Thermoelectric Materials, Thin Films, and Nanostructures I (Focused Session -- Organisers: Nielsch, Rastelli, Balke)

DS 59.3: Topical Talk

Friday, March 18, 2011, 12:00–12:30, GER 37

Thermal transport and thermoelectric effect in thin semiconductor membranes — •Matthias Schmidt, Thorben Bartsch, Christian Heyn, and Wolfgang Hansen — Institut für Angewandte Physik, Universität Hamburg, Germany

We study the heat conductance and the thermopower in single-crystalline semiconductor membranes which are fabricated by selective etching of AlGaAs-based heterostructures. The membranes have thicknesses up to a few 100 nm and are grown by molecular beam epitaxy. An airgap of thickness between 5 nm and 500 nm separates the membranes from the substrate and makes possible to establish large thermal gradients both to the substrate as well as within the membrane. In particular, the heat transport between a membrane that is held by few nanometer thin semiconductor columns and the substrate is studied. Furthermore, in thin semiconductor bridges containing a two-dimensional electron system the magneto-thermopower is investigated. The results demonstrate that we are able to establish strong thermal gradients even at very low temperature. With curved membranes in magnetic fields we can establish a system in which the spatial distribution of both the local density of states and the temperature can be controlled simultaneously.