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Title: In-situ four-tip STM investigation of the transition from 2D to 3D charge transport in SrTiO3
Authors: Leis, Arthur
Rodenbücher, Christian
Szot, Krzysztof
Cherepanov, Vasily
Tautz, F. Stefan
Voigtländer, Bert
Keywords: SrTiO3; In-situ
Issue Date: 2019
Citation: Scientific Reports, Vol. 9 (2019), Art. No. 2476
Abstract: 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, distancedependent 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 <3 μm 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 possible underlying mechanisms are discussed, particularly with regard to non-intrinsic material properties depending on details of the sample preparation.
DOI: 10.1038/s41598-019-38888-x
ISSN: 2045-2322
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