Dresden 2009 – scientific programme

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DS: Fachverband Dünne Schichten

DS 26: Poster II

DS 26.12: Poster

Wednesday, March 25, 2009, 09:30–12:30, P5

Influence of defects on the properties of the conductivity of the LAO/STO interface — •Felix Gunkel, Keisuke Shibuya, Regina Dittmann, and Rainer Waser — Forschungszentrum Jülich, Institut für Festkörperforschung, Elektronische Materialien, 52425 Jülich

The interface between LaAlO₃ (LAO) and SrTiO₃ (STO) is the most prominent example for the realization of highly conducting interfaces between two insulating oxides (e.g. [1],[2]). At least, two approaches have been made to explain the local accumulation of charge. On the one hand, STO/LAO interfaces possess a polarity discontinuity chasing electrons to move into the interface; on the other hand, oxygen vacancies are known to provide conductivity in STO. We have grown LAO thin films on (001)-STO single crystal substrates by RHEED controlled LASER-MBE. Clear RHEED intensity oscillations as well as thickness oscillations in the XRD-spectra indicate layer-by-layer growth mode and a smooth surface. For a wide range of process conditions, the STO/LAO interface is found to be conducting. The impact of stoichiometry variation in the cation or rather in the oxygen sublattice is addressed by the variation of deposition energy density and oxygen background pressure during growth. We will discuss the influence of point defects as well as extended defects on the electrical properties of the interfaces.

[1] H.Y. Hwang, A. Ohtomo, Nature 427, 423-426, 2004

[2] J. Mannhart, S. Thiel, G. Hammerl, A. Schmehl, C.W. Schneider, Science 313, 1942-1945, 2006