Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 96: Focus Session: Surface Transport at the Atomic Scale
O 96.3: Vortrag
Freitag, 5. April 2019, 11:15–11:30, H15
In-situ four-tip STM investigation of the transition from 2D to 3D charge transport in SrTiO3 — •Arthur Leis1,2, Christian Rodenbücher1,2, Krzysztof Szot1,2, Vasily Cherepanov1,2, F. Stefan Tautz1,2, and Bert Voigtländer1,2 — 1Peter Grünberg Institut (PGI-3, PGI-7), Forschungszentrum Jülich, Germany — 2Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, Germany
The electrical properties of SrTiO3(100) single crystals were investigated in-situ at different stages of thermal reduction by means of a 4-tip STM. Using the tips of the STM as electrical probes, distance-dependent four-point measurements were performed at the surface of the crystal at room temperature after reduction by thermal treatment. For annealing temperatures T < 700°C, charge transport is confined to a surface region < 3mm below the surface. For reduction at T > 900°C a transition from a conducting 2D sheet with insulating bulk to a system with dominant 3D bulk conductivity is found. At an intermediate reduction temperature of T = 800°C, a regime with mixed 2D/3D contributions is observed in the distance-dependent resistance measurements. Describing the depth dependent conductivity with an analytical N-layer model, this regime of mixed 2D/3D conductivity is evaluated quantitatively under the assumption of an exponentially decaying conductivity profile, correlated with the previously observed depth dependent dislocation density in the sample. A non-monotonous temperature dependence of the 3D conductivity in the respective conducting layer is found and the underlying mechanism is discussed.