Regensburg 2013 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 12: Poster Session II: Functionalized semiconductor nanowires (jointly with HL); Resistive switching (jointly with DF, KR, HL); Thermoelectric materials

DS 12.15: Poster

Montag, 11. März 2013, 17:00–20:00, Poster B1

Transport through nano sized pillars — •Thorben Bartsch, Alina Wetzel, David Sonnenberg, Christian Heyn, and Wolfgang Hansen — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstraße 11, 20355 Hamburg, Germany

We fabricate GaAs nanopillars with typical lengths between 4-8 nm and diameters of about 100 nm using molecular beam epitaxy [1]. The pillars are linked to a GaAs substrate on one end and to a GaAs layer of variable thickness at the other end. The epitaxial growth of the structure ensures that there are no crystal interfaces at these contacts. The pillars are embedded in a matrix of AlAs that can be selectively removed with hydrofluoric acid.

When the AlAs matrix is removed, the pillars open a gap between the GaAs layer and the substrate [1]. Appling a thermal gradient across the gap, thermal transport through the pillars can be studied. Using the 3-omega method we verified that the thermal transport through the pillars is ballistic in a temperature range at least up to 150 K [2]. Here influences from variations of the heterostructure geometry, especially from variable top layer thicknesses are discussed.

Moreover, in case of doped structures, charge transport through the pillars between two charge reservoirs held at different electric potential can be studied. We present first results of electronic transport experiments. At low temperature, the conductance is found to strongly depend on the strength and orientation of a magnetic field.

[1] Ch. Heyn et al., Appl. Phys. Lett. 98, 033105 (2011)

[2] Th. Bartsch et al., Phys. Rev. Lett. 108, 075901 (2012)