Dresden 2011 – scientific programme

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DS: Fachverband Dünne Schichten

DS 43: Poster II: Thin Film Chalcogenide Photovoltaics; Thermoelectric Materials, Thin Films, and Nanostructures

DS 43.11: Poster

Wednesday, March 16, 2011, 15:00–17:30, P2

Thermal conductivity measurements on nano air gaps. — •Thorben Bartsch, Matthias Schmidt, Christian Heyn, and Wolfgang Hansen — Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany

Nano air gaps in thermoelectric devices are an attempt to enlarge the efficiency of thermoelectric devices by drastically lowering of the thermal conductivity [1]. We present thermal conductivity measurements on GaAs based nano air gap heterostructures. The investigated structure is grown by molecular beam epitaxy. It is composed of a 50 nm GaAs layer which quasi hovers above the underlying GaAs substrate. The GaAs layers are held in position by GaAs nanopillars. Two samples have been studied with an air gap of 4 and 6 nm thickness, respectively. The measurements were performed for temperatures between 20 K and 300 K via the 3ω - method. The thermal conductivity values are up to three orders of magnitude smaller than the corresponding bulk thermal conductivity. [1] T. Zeng, Appl. Phys. Lett. 88, 153104 (2006).