Atomic structure of conducting nanofilaments in TiO2 resistive switching memory

• Published in: Nature nanotechnology Vol. 5; no. 2; pp. 148 - 153
• Main Authors: Kwon, Deok-Hwang, Kim, Kyung Min, Jang, Jae Hyuck, Jeon, Jong Myeong, Lee, Min Hwan, Kim, Gun Hwan, Li, Xiang-Shu, Park, Gyeong-Su, Lee, Bora, Han, Seungwu, Kim, Miyoung, Hwang, Cheol Seong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-02-2010; Nature Publishing Group
• Subjects: 639/925/357/537; 639/925/357/995; Chemistry and Materials Science; Conductivity; Crystallization; Electric Conductivity; Electrochemistry - methods; Electrodes; Fourier Analysis; Low temperature; Materials Science; Metal oxides; Microscopy, Electron, Transmission; Nanostructures - ultrastructure; Nanotechnology; Nanotechnology - methods; Nanotechnology and Microengineering; Oxides - chemistry; Random access memory; Scanning electron microscopy; Semiconductor research; Surface Properties; Thin films; Titanium - chemistry; Titanium dioxide; Transmission electron microscopy
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/nnano.2009.456

Resistance switching in metal oxides could form the basis for next-generation non-volatile memory. It has been argued that the current in the high-conductivity state of several technologically relevant oxide materials flows through localized filaments, but these filaments have been characterized only indirectly, limiting our understanding of the switching mechanism. Here, we use high-resolution transmission electron microscopy to probe directly the nanofilaments in a Pt/TiO
2
/Pt system during resistive switching.
In situ
current–voltage and low-temperature (∼130 K) conductivity measurements confirm that switching occurs by the formation and disruption of Ti
n
O
2
n
−1
(or so-called Magnéli phase) filaments. Knowledge of the composition, structure and dimensions of these filaments will provide a foundation for unravelling the full mechanism of resistance switching in oxide thin films, and help guide research into the stability and scalability of such films for applications.
Nanoscale filaments with a Magnéli structure are shown to be responsible for resistance switching in thin films of TiO
2
, and the properties of the filaments are directly observed during the switching process.