Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.79: Poster

Dienstag, 15. März 2011, 18:00–21:00, P3

Strontium titanate surface and bulk modifications due to vacuum annealing — •Juliane Seibt, Florian Hanzig, Ralph Strohmeyer, Hartmut Stöcker, Barbara Abendroth, and Dirk C. Meyer — TU Bergakademie Freiberg, Institut für Experimentelle Physik, Leipziger Straße 23, 09596 Freiberg

Vacuum annealing is a widely used method to increase the electric conductivity of SrTiO₃ single crystals. The induced oxygen vacancies act as intrinsic donors and lead to n-type conductivity. Apart from the changed electric properties, however, also structural modifications arise from this treatment. Here, we try to summarize all such changes originating from the in-vacuum heat-treatment. Used characterization methods include atomic force microscopy, transmission electron microscopy, X-ray diffraction, ellipsometry, infrared and photoluminescence spectroscopy. Beside the expected variation of bulk properties, especially surface modifications could be detected. The intrinsic number of near-surface dislocations in the samples was reduced by vacuum annealing but the surface roughness increased due to a self-organized restructuring process. Furthermore, the photoluminescence spectra revealed dependencies on exposure time and surrounding atmosphere. The influence of adsorbed or intrinsic surface layers on the observed behaviour will be discussed.