Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 25: Quantum dots and wires: Optical properties II
HL 25.9: Vortrag
Dienstag, 27. März 2007, 16:15–16:30, H17
Time-resolved optical spectroscopy of lateral InGaAs quantum dot molecules — •Claus Hermannstädter1, Gareth Beirne1, Lijuan Wang2, Armando Rastelli2, Oliver Schmidt2, and Peter Michler1 — 1Institut für Strahlenphysik, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany
We demonstrate direct control over the level of lateral quantum coupling between two self-assembled InGaAs/GaAs quantum dots. These coupled systems which we refer to as lateral quantum dot molecules are, due to their unique growth technique, all aligned along the [1-10] crystal direction. Electrodes on the sample surface allow for the application of a lateral electric field. By applying an electric field parallel to the coupling-axis the degree of coupling can be manipulated as manifested by the shift of the emission energies and relative intensities of the characteristic photoluminescence lines [1]. Time-correlated single-photon counting experiments performed on single molecules provide access to both the rise and decay characteristics of the molecule emission lines. Typical decay times for the excitonic recombination are on the order of 1 ns, about half the latter value for biexcitonic recombination, and intermediate for charged excitonic recombination. An analysis of the exciton rise behavior strongly indicates that electron tunneling is the predominant coupling mechanism in the molecules.
[1] G. J. Beirne, C. Hermannstädter, L. Wang, A. Rastelli, O. G. Schmidt and P. Michler, Phys. Rev. Lett. 96, 137401 (2006).