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HL: Fachverband Halbleiterphysik
HL 31: Quantum dots and wires: Optical properties III
HL 31.2: Talk
Wednesday, March 28, 2007, 15:00–15:15, H17
Polarized emission lines from A- and B-type excitonic complexes in single InGaN/GaN quantum dots — •Momme Winkelnkemper1,2, Robert Seguin1, Sven Rodt1, Andrei Schliwa1, Lars Reißmann1, Andre Strittmatter1, Axel Hoffmann1, and Dieter Bimberg1 — 1Institut für Festkörperphysik, Technische Universität Berlin, D-10623 Berlin, Germany — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany
Nitride-based semiconductor nanostructures have been widely studied in the last decade and revolutionary optoelectronic devices have emerged from this effort.
In this talk we report on a combined experimental and theoretical study of the optoelectronic properties of single InGaN/GaN quantum dots (QDs). Using single-QD cathodoluminescence, complex spectra with up to five emission lines per QD are observed. The lines are polarized along the orthogonal crystal directions [1 1 -2 0] and [-1 1 0 0].
Realistic eight-band k.p calculations reveal that the polarization of the emission lines is owed to the valence band structure of wurtzite group-III nitrides and the strain distribution within the QDs; it can be explained by excitonic recombinations involving hole states which are either formed by the A or the B valence band. The mechanism responsible for the polarization is a general feature of all wurtzite nitride-based QDs and is essential for the understanding of recombination processes in nitride QDs.