Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.96: Poster

Donnerstag, 17. März 2011, 18:00–21:00, P4

Coupled Quantum Dots for Thermopower Measurements — •Holger Thierschmann, Luis Maier, Johannes Knorr, Mathias Mühlbauer, Hartmut Buhmann, and Laurens W. Molenkamp — Physikalisches Institut (EP3), Universität Würzburg, Germany

A detailed knowledge of the physics of quantum dots is of fundamental importance in modern solid state physics. For this purpose thermoelectric transport measurements are a powerful method since they are known to be more sensitive to details of the electronic structure than conventional conductance measurements. In recent years, thermoelectric transport measurements have revealed additional insight in a number of single quantum dot phenomena [1,2]. However, there are only few experiments that investigate the thermoelectric properties of two coupled quantum dots. To fill this gap, we have designed samples that enable us to perform conductance measurements as well as thermoelectric measurements on two parallel quantum dots. We use gate electrodes on top of a GaAs/AlGaAs interface 2DEG to define lateral quantum dots and to tune their size and coupling strength to their surrounding. The dots are situated adjacent to a heating channel through which a current is passed so that a temperature gradient across the dot can be provided. Detailed potential simulations were run on a number of different gate designs. The designs were realized using optical and e-beam lithography and the performance of the structures was analyzed in a dilution refrigerator at electron temperatures below 100 mK.

[1] R. Scheibner et al,. Phys. Rev. B 75, 041301 (2007)

[2] R. Scheibner et al., Phys. Rev. Lett. 95, 176602, (2005)