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Issue 34, 2015
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The influence of the local oxygen vacancy concentration on the piezoresponse of strontium titanate thin films

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Abstract

In this study, the influence of the local oxygen vacancy concentration on piezoresponse force microscopy (PFM) measurements was investigated. Ultra-thin single-crystalline SrTiO3 thin films were deposited on niobium doped SrTiO3 substrates and analyzed using a combined PFM and local conductive atomic force microscopy (LC-AFM) measurement setup. After applying different polarization voltages between ±2 V and ±5 V to the thin films, we simultaneously observed an anomalous contrast in the piezoresponse amplitude and phase signal as well as a changed local conductivity in the exact same region. Since classic ferroelectricity can be excluded as the reason for the observed contrast, an influence of the local oxygen vacancy concentration on the piezoresponse is considered. Additionally, the surface potential was measured using Kelvin probe force microscopy (KPFM) revealing a change in surface potential in the regions of the applied voltage. The observed relaxation of the surface potential over time was fitted to a local oxidation reaction of the previously reduced regions of the ultra-thin SrTiO3 film. We propose a model that relates the local oxygen vacancy concentration to the surface potential. The influence of the oxygen vacancy concentration on the PFM measurements is explained.

Graphical abstract: The influence of the local oxygen vacancy concentration on the piezoresponse of strontium titanate thin films

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Article information


Submitted
02 Jun 2015
Accepted
19 Jul 2015
First published
06 Aug 2015

Nanoscale, 2015,7, 14351-14357
Article type
Paper

The influence of the local oxygen vacancy concentration on the piezoresponse of strontium titanate thin films

M. Andrä, F. Gunkel, C. Bäumer, C. Xu, R. Dittmann and R. Waser, Nanoscale, 2015, 7, 14351
DOI: 10.1039/C5NR03643G

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