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HL: Halbleiterphysik

HL 14: II-VI semiconductors I

HL 14.2: Vortrag

Dienstag, 28. März 2006, 11:15–11:30, POT 151

Photoluminescence properties of Mg_xZn_1−xO thin films grown by pulsed laser deposition — •Susanne Heitsch, Gregor Zimmermann, Holger Hochmuth, Daniel Spemann, Gabriele Benndorf, Heidemarie Schmidt, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, D-04103 Leipzig, Germany

Mg_xZn_1−xO thin films (0 ≤ x ≤ 0.18) have been grown on a-plane sapphire substrates with or without ZnO buffer layers by pulsed laser deposition. The Mg content in the films was controlled by using different MgZnO targets and by applying different oxygen partial pressures p(O₂) during the deposition, respectively. Higher oxygen partial pressures caused a lower Mg content in the thin films. The surface roughness measured by AFM shows no dependence on x, but on p(O₂). A minimum could be found for samples grown at p(O₂) ∼ 1× 10⁻³ mbar. Samples with equal x grown at lower oxygen partial pressures show a broader photoluminescence (PL) emission than samples grown at higher pressures. With increasing x the PL maximum shifts approximately linearly to higher energies and the emission exhibits a broadening not only due to alloy broadening. The blueshift of the PL peak position on x is found to be larger at room temperature than at 2 K. Deposition of the Mg_xZn_1−xO thin films on ZnO buffer layers improves the surface quality as well as the half width of the emission.