Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 52: Quantum dots and wires: Optical properties IV

HL 52.6: Vortrag

Freitag, 31. März 2006, 12:15–12:30, POT 151

Systematic size-dependence of anisotropic exchange interaction in InAs/GaAs quantum dots — •Robert Seguin, Sven Rodt, Andrei Schliwa, Konstantin Pötschke, Udo W. Pohl, and Dieter Bimberg — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

A comprehensive study of the exchange interaction of charge carriers in self-organized InAs/GaAs quantum dots (QDs) is presented. Single QDs are examined by means of cathodoluminescence applying metallic shadow masks. The spectra reveal a systematic dependence of the anisotropic exchange interaction on QD size.

The exchange interaction in nanostructures has been subject of a lively debate in recent years. Its anisotropic part governs the excitonic fine-structure splitting (fss), the key parameter determining the suitability of QDs for quantum cryptography, and the degree of polarization of excited charged excitons (trions) in QDs. While the number of participating particles varies between two (excitons) and three (trions), the underlying physical effect is the same. We show that the magnitude of the excitonic fss and the degree of polarization of excited trions are indeed correlated. They both increase with decreasing exciton recombination energy and thus increasing with quantum dot size.