Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 104: Quantum Dots and Wires: Optical Properties V (mainly Indiviual Photons)
HL 104.5: Vortrag
Freitag, 30. März 2012, 12:45–13:00, EW 201
Two-photon emission from single GaN quantum dots — •Gordon Callsen1, Juri Brunnmeier1, Andrei Schliwa1, Johannes Settke1, Christian Kindel1, Erik Stock1, Alexander Dreismann1, Satoshi Kako2, Yasuhiko Arakawa2, and Axel Hoffmann1 — 1Institut für Festkörperphysik, Technische Universität Berlin, Germany — 2Institute of Industrial Science, University of Tokyo, Japan
Recent reports on single photon emission of MOCVD grown GaN quantum dots embedded in an AlN matrix at elevated temperatures (> 200 K) resulted rising interest in such quantum dots with large exciton binding energy, oscillator strength and band-offset. Simultaneous observation of excitonic and biexcitonic emission in µPL-spectra allows direct determination of the strain state and size of the quantum dot. As characteristic for wurzite GaN/AlN quantum dots the biexciton binding energy varies between +3 meV and -11 meV. This transition of the biexciton binding energy from the binding to the antibinding case facilitates a spectral window in which the technologically desirable colour-coincidence of the exciton and the biexciton can be observed. We analyse the exciton-biexciton cascade in single GaN quantum dots which yields the observation of the emission of a photon couple in a narrow (< 2 ns) time interval as demonstrated by photon-correlation measurements based on a Hanbury-Brown & Twiss setup. In detail analysis of the bunching signal of the autocorrelation experiments allows us to deduce the temporal evolution of the cascade process depending on temperature and excitation density variation.