Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 52: Quantum dots and wires: Optical properties IV

HL 52.12: Talk

Friday, March 31, 2006, 13:45–14:00, POT 151

Lifetime of localized excitons in InGaN quantum dots — •M. Dworzak, M. Winkelnkemper, A. Hoffmann, and D. Bimberg — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin

At low temperature indium-rich fluctuation islands in a 2 nm thick InGaN layer form a quantum dot (QD) ensemble of ultra-high density. Regarding the recombination dynamic of localized excitons these QDs differ extremely from other QD systems. Spatially resolved investigations on single InGaN QDs by means of time-resolved photoluminescence (TRPL) showed a broad distribution of the exciton lifetimes, even for QDs with similar transition energy. [1]

On one hand this behavior is causes by different electron/hole wave-function overlaps due to the disordered distribution of QD size, shape and indium content inside the QD ensemble. This is modeled by 8-band kp theory. On the other hand TRPL studies showed redistribution of carriers between the QDs. Thus, also different transfer probabilities inside the QD ensemble lead to different time constants.

[1] Bartel et al., Appl. Phys. Lett. 85, 1946 (2004)