Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 37: Quantum Dots and Wires: Optical Properties III
HL 37.2: Vortrag
Mittwoch, 24. März 2010, 09:45–10:00, H15
Fine Structure Splitting of Neutral Excitons in GaAs/AlGaAs Quantum Dots — •Johannes D. Plumhof1, Vlastimil Krapek1,2, Lijuan Wang1,3, Andrei Schliwa4, Armando Rastelli1, and Oliver G. Schmidt1 — 1Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden — 2Institute of Condensed Matter Physics, Masaryk University, Kotlarska 2, 61137 Brno, Czech Republic — 3Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569 Stuttgart — 4Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin
For the generation of polarization entangled photon pairs using self-assembled semiconductor quantum dots (QDs) it is important to decrease the fine structure splitting (FSS) energy of the neutral exciton to values lower than the emission linewidth. We study here the behaviour of the FSS of strain-free, molecular beam epitaxy grown GaAs/AlGaAs QDs. We use polarization-dependent photoluminescence spectroscopy to investigate the FSS of a large number of QDs. Based on AFM images of QDs grown under nominally same conditions we demonstrate the statistic interrelation of QD-shape and FSS. Due to the well known shape and composition profile of the QDs we are able to reproduce the experimental results with 8 band kp-simulations using the realistic structure as input. We also study the polarization of the light emitted by excitons confined in quantum well thickness fluctuations with not well defined shape to estimate the possible influence of effects on FSS other than shape, such as alloy ordering.