Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 70: Quantum Dots and Wires: Theory
HL 70.6: Talk
Thursday, March 17, 2011, 11:30–11:45, POT 151
Interrelation of Biexciton Binding Energies and Structural Properties of GaN/AlN Quantum Dots — •Gerald Hönig, Christian Kindel, Momme Winkelnkemper, Andrei Schliwa, Sven Rodt, Irina Ostapenko, Axel Hoffmann, and Dieter Bimberg — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany
Nitride-based quantum dots (QDs) are very promising candidates for high-temperature stable, entangled photon pair emitters. Tuning the biexciton energy (Exx) by varying structural parameters [1] is of largest importance for QDs in microcavities, where the emission has to match the cavity-mode. The experimental observation of a sign change of the biexciton binding energy (Ebind:= 2Ex − Exx, with Ex:= exciton energy) in GaN/AlN QDs [2], is theoretically not understood so far. We are able to investigate this feature by using a configuration interaction scheme (CI) based on self-consistent 8-band-k· p Hartree-Fock (HF) states. The self-consistency is crucial since built-in piezo- and pyroelectric fields (on the order of MV/cm) cause a spatial separation between electrons and holes within nitride-based QDs, making a CI basis of renormalised HF states superior to single particle wave functions. We take a close look on different structural parameters influencing Exx as well as the quantity of correlation effects in GaN/AlN QDs. Both, positive and negative biexciton binding energies are possible for respective QD structures. Funded by SFB 787.
[1] A. Schliwa, et al., Phys. Rev. B 79, 075443 (2009)
[2] D. Simeonov, et al., Phys. Rev. B 77, 075306 (2008)