Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Metal Oxide Surfaces I: Structure, Epitaxy and Growth

O 27.3: Vortrag

Dienstag, 2. April 2019, 11:00–11:15, H16

Atomically-resolved AFM study of the bulk-terminated SrTiO₃ (001) 1x1 surface — •Igor Sokolović, Michael Schmid, Ulrike Diebold, and Martin Setvin — Institute of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria

Working with bulk-terminated perovskite surfaces is challenging since the surface preparation techniques suitable for preparation of binary oxide surfaces lead to a plethora of surface reconstructions. We successfully cleaved the prototypical cubic perovskite oxide, SrTiO₃ (STO), by utilizing strain-induced ferroelectricity, and possibly found a way to cleave other cubic perovskites with no preferable planes of cleavage. The bulk-terminated (1x1) STO (001) surface was investigated by non-contact atomic force microscopy (ncAFM) which reveals that the as-cleaved surface consists of two distinct terminations: terraces with a metallic TiO₂ and a semiconducting SrO termination, both being up to micrometers in size. During the cleaving Sr atoms are pulled out of the top SrO layer and remain on the opposite TiO₂ surface in the form of adatoms; the concentration of these Sr adatoms is the same as the concentration of Sr vacancies on the SrO surface. These charged point defects serve as a polarity compensation mechanism for stabilizing the strain-induced polarity along the [001] direction in the crystal. Annealing the surface gradually alters the (1x1) termination and turns the surface amorphous.