Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Optical properties
HL 13.6: Vortrag
Dienstag, 24. März 2009, 10:45–11:00, BEY 118
Electronic coupling in ZnO/MgZnO Double Quantum Wells — •Jan Zippel, Martin Lange, Gabriele Benndorf, Jörg Lenzner, Holger Hochmuth, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II,Linnéstraße 5, 04103 Leipzig
The band-gap of ZnO can be tuned from about 3 eV to 4.5 eV by alloying with Cd or Mg, respectively. This allows the realization of quantum well (QW) structures emitting between the blue and the near UV (NUV) part of the electromagnetic spectrum. In this contribution we focus on the electronic coupling of ZnO/MgxZn1−xO double quantum well (DQW) structures. Besides structures with two identical wells, we fabricated DQW*s with different thickness. All samples were grown by pulsed-laser deposition on a-plane sapphire substrate. The thickness of the barrier between the two QWs was varied from 1 nm up to 6 nm for well widths of 2 nm and 4.5 nm. The magnesium content (x) in the barrier was determined by photoluminescence measurements to be about 14% for all samples [1].
All samples are investigated using cathodoluminescence at room temperature and at 10 K. With decreasing barrier thickness between the two QWs we observed a clear red shift of the QW luminescence proving the coupling between the QWs at room temperature. The observed shift is in good agreement with effective mass theory. For the structures with different well width, an additional peak between the two direct excitonic transitions occurs.
[1] S. Heitsch et al., J. Appl. Phys. 101, 083521 (2006).