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HL: Fachverband Halbleiterphysik

HL 25: Quantum dots and wires: Optical properties II

HL 25.5: Talk

Tuesday, March 27, 2007, 15:00–15:15, H17

Thermal annealing of selected individual quantum dots — •Robert Seguin, Andrei Schliwa, Tim Germann, Sven Rodt, Konstantin Pötschke, Udo Pohl, and Dieter Bimberg — Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, D-10623 Berlin, Germany

Cathodoluminescence spectra of single InAs/GaAs quantum dots were recorded before and after consecutive thermal annealing steps. The annealing process leads to an overall blueshift of the spectra indicating In/Ga interdiffusion. Excitonic fine-structure splitting and binding energies of charged and neutral excitonic complexes were monitored. A drastic reduction of the fine-structure splitting from 170 µeV to less than 20 µeV can be observed accompanied by a change of the character of the biexciton from anti-binding to binding with respect to the exciton. Tailoring the fine-structure splitting is especially important for the use of single quantum dots in opto-electronic devices for quantum key distribution where a degeneracy of the exciton ground state (i.e. a fine-structure splitting below the homogeneous linewidth) is required for the on-demand production of entangled photon pairs.