title: In situ TEM imaging of defect dynamics under electrical bias in resistive switching rutile-TiO₂.
abstract: 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.
authors.affiliation: 1Materials Science and Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: Ranga J
authors.initials: RJ
authors.lastname: Kamaladasa
authors.affiliation: 2Electrical and Computer Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: Abhishek A
authors.initials: AA
authors.lastname: Sharma
authors.affiliation: 1Materials Science and Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Lai
authors.affiliation: 1Materials Science and Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: Wenhao
authors.initials: W
authors.lastname: Chen
authors.affiliation: 1Materials Science and Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Salvador
authors.affiliation: 2Electrical and Computer Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Bain
authors.affiliation: 1Materials Science and Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: Marek
authors.initials: M
authors.lastname: Skowronski
authors.affiliation: 1Materials Science and Engineering,Carnegie Mellon University,5000 Forbes Avenue,Pittsburgh,PA 15213,USA.
authors.forename: Yoosuf N
authors.initials: YN
authors.lastname: Picard
keywords: Wadsley defects