In Situ TEM Imaging of Defect Dynamics under Electrical Bias in Resistive Switching Rutile-TiO2

In this study, in situ electrical biasing was combined with transmission electron microscopy (TEM) in order to study the formation and evolution of Wadsley defects and Magnéli phases during electrical biasing and resistive switching in titanium dioxide (TiO2). Resistive switching devices were fabric...

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Bibliographic Details
Published in:Microscopy and microanalysis 2015-02, Vol.21 (1), p.140-153
Main Authors: Kamaladasa, Ranga J., Sharma, Abhishek A., Lai, Yu-Ting, Chen, Wenhao, Salvador, Paul A., Bain, James A., Skowronski, Marek, Picard, Yoosuf N.
Format: Article
Language:English
Subjects:
Bias
Electrodes
Evolution
Fourier transforms
Grain boundaries
Materials Applications
Metal oxides
Oxygen
Point defects
Random access memory
Thin films
Titanium dioxide
Transmission electron microscopy
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Summary:In this study, in situ electrical biasing was combined with transmission electron microscopy (TEM) in order to study the formation and evolution of Wadsley defects and Magnéli phases during electrical biasing and resistive switching in titanium dioxide (TiO2). Resistive switching devices were fabricated from single-crystal rutile TiO2 substrates through focused ion beam milling and lift-out techniques. Defect evolution and phase transformations in rutile TiO2 were monitored by diffraction contrast imaging inside the TEM during electrical biasing. Reversible bipolar resistive switching behavior was observed in these single-crystal TiO2 devices. Biased induced reduction reactions created increased oxygen vacancy concentrations to such an extent that shear faults (Wadsley defects) and oxygen-deficient phases (Magnéli phases) formed over large volumes within the TiO2 TEM specimen. Nevertheless, the observed reversible formation/dissociation of Wadsley defects does not appear to correlate to resistive switching phenomena at these length scales. These defect zones were found to reversibly reconfigure in a manner consistent with charged oxygen vacancy migration responding to the applied bias polarity.
ISSN:1431-9276
1435-8115
DOI:10.1017/S1431927614013555