Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 91: Poster Session: Quantum dots and wires: preparation & characterization & optical properties & transport properties
HL 91.25: Poster
Donnerstag, 14. März 2013, 16:00–20:00, Poster A
Thermoelectric Properties of a Strongly Coupled Double Quantum Dot — •Holger Thierschmann1, Michael Henke1, Johannes Knorr1, Wolfgang Hansen2, Hartmut Buhmann1, and Laurens W. Molenkamp1 — 1Physikalisches Institut, Experimentelle Physik 3, Universität Würzburg — 2Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg
We study the thermoelectric properties of a double quantum dot (DQD) in the low temperature regime under a temperature difference of a few 10 mK. Our sample consists of a lateral DQD system defined electrostatically by gate electrodes on top of a GaAs/AlGaAs-HEMT structure. By measuring the serial conductance of the DQD we yield a stability diagram from which we can extract the charging and coupling energies. We infer that the system is in the strong tunnelcoupling regime. For thermopower measurements we use the current heating technique to establish a temperature difference of approx. 20 mK across the DQD structure [1]. Measuring the thermovoltage across the serial DQD, we obtain a thermopower stability diagram. We find maximum thermovoltage in the corners of each stability region. In the vicinity of a tripel point we observe a strong asymmetry of the thermovoltage signal. This can be traced back to an asymmetric distribution of energy levels with respect to the Fermi-energy in the DQD system which is consistent within a simple DQD model.
[1] L.W. Molenkamp, H. van Houten, C.W.J. Beenakker, R. Eppenga, C.T Foxon, PRL 65, 1052(1990)