Dresden 2009 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 6: Poster I

DF 6.2: Poster

Tuesday, March 24, 2009, 09:30–12:30, P5

Electronic defect state mapping in strontium titanate by surface photovoltage and photoconductivity spectra — •Jana Becherer, Elke Beyreuther, Andreas Thiessen, Stefan Grafström, and Lukas M. Eng — Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden, Germany

Within the current interest in the field of oxide electronics, strontium titanate (SrTiO₃, STO) plays a crucial role as a substrate for the epitaxy of a wide variety of perovskite oxide films on the one hand and as a functional oxide by itself on the other hand. However, the electronic properties of STO – though having been the subject of research for several decades – are still not well understood for several reasons: (i) Firstly, the electronic properties change dramatically as a function of oxygen content, doping, or surface treatments, while (ii) secondly, standard electrical characterization methods fail due to the wide band gap and the consequently low carrier concentration. Thus optical techniques are the methods of choice for this kind of material.

In order to gain a more systematic understanding of surface and bulk electronic defect states, we performed a comparative study of the spectral, temporal, and temperature dependence of the surface photovoltage and the photoconductivity of undoped and doped STO single crystals. We discuss the defect state distribution within the framework of a classical band scheme.