Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Optical properties

HL 13.9: Talk

Tuesday, March 24, 2009, 11:45–12:00, BEY 118

Time-resolved photoluminescence on ZnO based quantum well structures — •Marko Stölzel, Alexander Müller, Jan Zippel, Gabriele Benndorf, Holger Hochmuth, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany

We have investigated the optical properties of MgZnO/ZnO QW structures using time-resolved photoluminescence (TRPL) to understand recombination in these heterostructures. The layers have been grown with a ZnO buffer layer on a-plane sapphire substrate by pulsed laser deposition.

TRPL was excited by a frequency-doubled/tripled femtosecond Ti:Sa laser tuned to resonant and nonresonant excitation. For resonant excitation the QW behaves mono-exponential. When the barrier is excited, the QW decay is superposed by a slow non-exponential decay which matches the temporal behavior of the barrier luminescence. Temperature dependent measurements show a decrease of the exciton lifetime in the QW for increasing temperatures due to nonradiative recombination.

We compare this single QW with a set of symmetric double-QWs seperated by barriers of different thicknesses. For large barriers they behave like a single QW. In the case of small barriers (< 6nm) the peak of the QW luminescence shifts towards lower energies and a second non-exponential decay appears in addition to the mono-exponential decay of the QW. This is taken as an indication for the coupling.