Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 21: Quantum Dots and Wires, Optical Properties I: Nitrides
HL 21.6: Vortrag
Dienstag, 23. März 2010, 10:45–11:00, H17
Complete Study of Excitonic Fine-Structure Splitting in GaN/AlN Quantum Dots — •Gerald Hönig1, Momme Winkelnkemper1, Andrei Schliwa1, Axel Hoffmann1, Dieter Bimberg1, Christian Kindel1,2, Satoshi Kako3, Takeshi Kawano2, Hiroaki Oishi2, and Yasuhiko Arakawa2,3,4 — 1Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany — 2Research Center for Advanced Science and Technology, University of Tokyo, Japan — 3Institute for Nano Quantum Information Electronics, University of Tokyo, Japan — 4Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan
A detailed understanding of the excitonic fine structure in quantum dots (QDs) is indispensable for their use in quantum cryptography devices. While the fine structure in As-based QDs has been studied extensively, there is a lack of such investigations for N-based QDs, which might operate at room temperature. We present the first complete study of excitonic fine-structure splitting (FSS) in GaN/AlN QDs. Our experimental studies reveal a huge FSS of up to 7meV with a strong dependence on the emission energy inverse to that in As-based QDs. Our theoretical studies, performed with a configuration-interaction method based on realistic 8-band-k· p Hartree-Fock states, confirm the experimental results and identify the origin of FSS as lattice strain induced. Based on our results it is possible to induce a strain gradient (by micro mechanic techniques or structuring methods), which will reduce the FSS to zero for the emission of entangled photon pairs.