Journal Article

FZJ-2019-01643

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png In-situ four-tip STM investigation of the transition from 2D to 3D charge transport in SrTiO3

Leis, A.FZJ* ; Rodenbücher, C.FZJ* ; Szot, K.FZJ* ; Cherepanov, V.FZJ* ; Tautz, F. S.FZJ* ; Voigtländer, B. (Corresponding author)FZJ*

2019
Macmillan Publishers Limited, part of Springer Nature [London]

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Please use a persistent id in citations: http://hdl.handle.net/2128/21719  doi:10.1038/s41598-019-38888-x

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, 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 <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.

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Contributing Institute(s):

1. Funktionale Nanostrukturen an Oberflächen (PGI-3)
2. Elektrochemische Verfahrenstechnik (IEK-3)

Research Program(s):

1. 141 - Controlling Electron Charge-Based Phenomena (POF3-141) (POF3-141)
2. 135 - Fuel Cells (POF3-135) (POF3-135)

Appears in the scientific report 2019

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