Berlin 2008 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 17: Poster I
HL 17.19: Poster
Monday, February 25, 2008, 16:30–19:00, Poster D
Structural and optical properties of ZrO2 and Al2O3 thin films and Bragg reflectors grown by pulsed laser deposition — •Jan Sellmann, Chris Sturm, Rüdiger Schmidt-Grund, Helena Hilmer, Holger Hochmuth, Christian Czekalla, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig
Our objective is to build a threshold-less laser based on the emission from a Bose-Einstein condensate of exciton-polaritons in a semiconductor microcavity-resonator. For this purpose, high reflective mirrors with smooth boundaries are necessary. The aspired resonator structure consists of a half-wavelength ZnO cavity embedded between two ZrO2/Al2O3 Bragg reflectors.
We present high-reflective ZrO2/Al2O3 Bragg reflectors grown by pulsed laser deposition on c-plane sapphire and silicon substrates. For ZrO2/Al2O3 Bragg reflectors with a layer pair number of 12.5, reflectivity values of 99.8% at 3.3 eV and smooth surfaces have been reached. As preceding investigations, the optical and structural properties as the refractive indices, the crystal structure, and the surface properties of the used materials have been determined and optimised. It was found that these properties depend on the substrate and the position in the Bragg reflector layer stack.
The optical and structural properties of the single layers and Bragg reflectors have been gained from spectroscopic ellipsometry in the energy range (1.0-4.5) eV, X-ray diffraction measurements, atomic force microscopy, and transmission scanning electron microscopy.