Dresden 2014 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 19: Invited Talk - Elke Beyreuther

DF 19.1: Hauptvortrag

Donnerstag, 3. April 2014, 09:30–10:15, GER 37

Analyzing electronic defect states at perovskite oxide interfaces by surface photovoltage spectroscopy — •Elke Beyreuther and Lukas Eng — Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden, Germany

Surface photovoltage (SPV) spectroscopy, being a versatile method to analyze the energetic distribution of electronic defect states at surfaces and interfaces of wide-bandgap semiconductor (hetero-)structures, is discussed as an alternative approach for studying perovskite oxide surfaces and interfaces [1]. In particular, the method is applied to comparatively investigate prototypical heterostructures made of 5-unit-cell-thick LaAlO₃ films grown on either TiO₂- or SrO-terminated SrTiO₃. As shown by a number of experimental and theoretical investigations in the past, these two systems exhibit dramatically different interface properties with the first establishing a conducting interface and the second being insulating. The present SPV investigation reveals clearly distinguishable interface defect state distributions for both configurations within the framework of a classical semiconductor band scheme. Furthermore, bare SrTiO₃ crystals with TiO₂ or mixed SrO/TiO₂ terminations show similar SPV spectra and transients as the LaAlO₃ covered samples with the respective termination of the SrTiO₃ substrate [2]. This is in accordance with a number of recent works, which stress the decisive role of the SrTiO₃ and the minor role of the LaAlO₃ for the electronic properties of the interface.

[1] E. Beyreuther et al., Surf. Sci. 612, 1–9 (2013).

[2] E. Beyreuther et al., arXiv:1311.0491 [cond-mat.mtrl-sci] (2013).