Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 97: Quantum Dots and Wires: Optical Properties IV (mainly Nitrides)
HL 97.1: Vortrag
Freitag, 30. März 2012, 10:00–10:15, ER 270
Exciton-Phonon coupling in single GaN quantum dots — •Juri Brunnmeier1, Gordon Callsen1, Andrei Schliwa1, Johannes Settke1, Christian Kindel1, Erik Stock1, Satoshi Kako2, Yasuhiko Arakawa2, and Axel Hoffmann1 — 1Institut für Festkörperphysik, Technische Universität Berlin, Germany — 2Institute of Industrial Science, University of Tokyo, Japan
Recently, single photon emission of MOCVD grown GaN quantum dots embedded in an AlN matrix was observed at elevated temperatures (> 200 K) which represents a strong technological advantage in comparison to the well established system of arsenide quantum dots. However, to this day single photon emission of GaN quantum dots at room temperature seems to be hindered by a combination of various effects as the excitonic interaction with defects situated in the vicinity of the GaN quantum dot and a comparably strong exciton-phonon interaction. As a measure of the exciton-LO-phonon coupling strength we determine Huang-Rhys factors between 0.02 and 0.3, scaling with the size of the individual quantum dot, it’s emission energy and the related dipole-moment, which is up to 3 orders of magnitude larger than in the arsenide quantum dot system. Furthermore, we compare measured values for the Huang-Rhys factor for a statistically valid (> 100) number of single GaN quantum dots with eight-band k·p model based calculations. As a result we gain detailed insight into the strong piezo- and pyroelectrical fields which are characteristic for wurzite GaN/AlN quantum dots.