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HL: Fachverband Halbleiterphysik

HL 57: Focussed Session: ZnO-based Semiconductors

HL 57.7: Talk

Thursday, March 25, 2010, 16:15–16:30, H17

Quantum confined Stark effect in ZnO/MgZnO quantum wells fabricated with different growth processes — •Marko Stölzel, Matthias Brandt, Alexander Müller, Michael Lorenz, Gabriele Benndorf, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig, Germany

The properties of quantum wells (QWs) are very sensitive to the interface quality. Ideally, atomically flat interfaces are required to enclose a perfect square well. In the ZnO/MgZnO system the potential landscape changes into a triangular potential due to the electric polarization difference between both materials and the resulting electric field. The quantum confined stark effect (QCSE) is therefore expected to be observed in such heterostructures. Its presence and the related phenomena can be used as a criterion for the interface quality. In the present study QW-structures were grown by PLD directly on sapphire, on a ZnO buffer layer on sapphire and on O-polar ZnO single crystal substrates. The surface morphology was investigated by AFM. Structural quality was assessed by HR-XRD. All samples were grown pseudomorphically and in the step flow mode, excluding major influences from interface roughening.

The occurrence of the QCSE has been determined by intensity-dependent as well as time-resolved photoluminescence measurements. A redshift of the QW luminescence as well as an immense increase in the exciton lifetime is observed for high quality samples.