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Unraveling the Origin and Mechanism of Nanofilament Formation in Polycrystalline SrTiO 3 Resistive Switching Memories
Author(s) -
Kwon DeokHwang,
Lee Shinbuhm,
Kang Chan Soon,
Choi Yong Seok,
Kang Sung Jin,
Cho Hae Lim,
Sohn Woonbae,
Jo Janghyun,
Lee SeungYong,
Oh Kyu Hwan,
Noh Tae Won,
De Souza Roger A.,
Martin Manfred,
Kim Miyoung
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201901322
Subject(s) - protein filament , materials science , crystallite , transmission electron microscopy , electrode , resistive touchscreen , grain boundary , condensed matter physics , phase (matter) , scanning transmission electron microscopy , polarization (electrochemistry) , electron energy loss spectroscopy , chemical physics , nanotechnology , composite material , microstructure , chemistry , metallurgy , physics , electrical engineering , engineering , organic chemistry
Three central themes in the study of the phenomenon of resistive switching are the nature of the conducting phase, why it forms, and how it forms. In this study, the answers to all three questions are provided by performing switching experiments in situ in a transmission electron microscope on thin films of the model system polycrystalline SrTiO 3 . On the basis of high‐resolution transmission electron microscopy, electron‐energy‐loss spectroscopy and in situ current–voltage measurements, the conducting phase is identified to be SrTi 11 O 20 . This phase is only observed at specific grain boundaries, and a Ruddlesden–Popper phase, Sr 3 Ti 2 O 7 , is typically observed adjacent to the conducting phase. These results allow not only the proposal that filament formation in this system has a thermodynamic origin—it is driven by electrochemical polarization and the local oxygen activity in the film decreasing below a critical value—but also the deduction of a phase diagram for strongly reduced SrTiO 3 . Furthermore, why many conducting filaments are nucleated at one electrode but only one filament wins the race to the opposite electrode is also explained. The work thus provides detailed insights into the origin and mechanisms of filament generation and rupture.