Berlin 2012 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 13: Poster II

DF 13.11: Poster

Wednesday, March 28, 2012, 15:00–17:30, Poster E

Identification of electronic defect states in perovskite oxides — •Elke Beyreuther, Jana Becherer, Stefan Grafström, and Lukas M. Eng — Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden, Germany

Perovskite oxide heterojunctions such as the LaAlO₃/SrTiO₃ interface have attracted enormous scientific interest due to their unexpected and tunable physical properties but equally because of their technological promises with respect to all-oxide integrated nanodevices. Among other unresolved issues, the detailed physical understanding of the electronic defect structure at these interfaces is indispensable.

We adopt here the surface photovoltage (SPV) method to inspect the surfaces and interfaces of SrTiO₃ (STO), which serves as our model perovskite. SPV has already substantially contributed to the analysis of III-V and II-VI semiconductor interfaces, both through spectrally and temporally resolved investigations. Here, we investigated the STO system by acquiring static and transient SPV data over a wide wavelength range and for various light intensities. This allowed us to identify and quantify defect states across the STO band gap, and to derive parameters of distinct states such as optical cross sections and time constants. The feasibility and general possibilities of applying SPV for the analysis of perovskite heterostructures will be discussed.