Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 43: Quantum dots and wires: Optical properties II

HL 43.4: Talk

Thursday, February 28, 2008, 14:45–15:00, EW 201

Decay dynamics of neutral and charged excitonic complexes in single InAs/GaAs QDs — •Max Feucker, Robert Seguin, Sven Rodt, Konstantin Pötschke, and Dieter Bimberg — Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany

Across the inhomogeneously broadened lineshape of a quantum dot (QD) ensemble the decay times are expected to vary since the wavefunctions and the oscillator strengths are sensitive to the actual geometry of the QD. We performed time-resolved cathodoluminescence spectroscopy of 26 different single InAs/GaAs QDs to investigate the decay dynamics of neutral and charged excitonic complexes. The largest decay rate was found for the XX+, followed by XX, X+ and finally the X. We will show that the ratios of lifetimes of the different excitonic complexes are mainly governed by the number of involved recombination channels. There is excellent agreement between the measured and predicted values for the lifetime ratios of the neutral (X/XX) and the positively charged (X+/XX+) complexes. Surprisingly the lifetime of the exciton (X) shows a much larger yet unexplained scatter than that of all the other complexes.