Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 28: ZnO: preparation and characterization I
HL 28.9: Vortrag
Mittwoch, 25. März 2009, 12:00–12:15, BEY 118
Identification of excitonic transitions in MgxZn1−xO thin films grown by pulsed laser deposition — •Christof Dietrich, Gabriele Benndorf, Jörg Lenzner, and Marius Grundmann — Universität Leipzig, Semiconductor Physics Group, Institut für Experimentelle Physik II, Leipzig, Germany
The incorporation of Mg-atoms into ZnO leads to an increase of the band-gap allowing a tuning between 3,4 eV and about 8 eV. Nevertheless the recombination mechanisms in MgZnO are not yet well understood because alloy broadening superimposes spectral information.
In order to obtain more information about the recombination mechanisms, MgZnO thin films with a low Mg-content (1 - 7 %) were grown on a-plane sapphire substrates by pulsed-laser deposition. Buffer layers containing about 40 % Mg were deposited prior to the thin films. The Mg-contents were determined by energy dispersive x-ray diffraction spectroscopy.
Photoluminescence measurements at 2 K showed two peaks with a separation of 15 meV in the excitonic regime which we attribute to the transitions of the free and the Al-donor bound excitons. Temperature dependent photoluminescence measurements from 5 K up to room temperature confirmed this and revealed a S-shape behaviour for the donor bound exciton only.