Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 28: ZnO: preparation and characterization I
HL 28.2: Vortrag
Mittwoch, 25. März 2009, 09:45–10:00, BEY 118
Growth and Characterization of ZnO/ZnMgO Quantum Wells — •Bernhard Laumer1, Thomas A. Wassner1, Jochen Bruckbauer1, Martin Stutzmann1, and Martin Eickhoff2 — 1Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany — 2I. Physikalisches Institut, Justus-Liebig-Universität, Heinrich-Buff-Ring 16, 35392 Giessen, Germany
ZnO/Zn1−xMgxO quantum wells (QWs) were grown on c-plane sapphire substrates by plasma assisted molecular beam epitaxy (PAMBE). In order to obtain smooth interfaces, growth was initiated by deposition of a thin MgO/ZnO double buffer and a thick ZnO intermediate layer. This was followed by the actual Zn1−xMgxO/ZnO/Zn1−xMgxO QWs with Mg contents x up to 0.18. The ZnMgO barriers were found to grow pseudomorphically. The photoluminescence (PL) spectra taken at 4.2 K are dominated by an emission line that is blue-shifted with respect to the ZnO emission and that is attributed to localized excitons in the QWs. Increasing the Mg content x in the barrier results in a blue-shift of the QW emission, as expected from quantum confinement. Temperature-dependent PL measurements show that at higher temperatures the emission of free excitons prevails. Furthermore, an emission line (D) below that of ZnO with pronounced phonon replica appears, which red-shifts with increasing x.