In situ observation of filamentary conducting channels in an asymmetric Ta2O5−x/TaO2−x bilayer structure

• Published in: Nature communications Vol. 4; no. 1; p. 2382
• Main Authors: Park, Gyeong-Su, Kim, Young Bae, Park, Seong Yong, Li, Xiang Shu, Heo, Sung, Lee, Myoung-Jae, Chang, Man, Kwon, Ji Hwan, Kim, M., Chung, U-In, Dittmann, Regina, Waser, Rainer, Kim, Kinam
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.09.2013; Nature Publishing Group
• Subjects: 639/301/357/551; 639/925/357/995; Fabrication; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms3382

Electrically induced resistive switching in metal insulator-metal structures is a subject of increasing scientific interest because it is one of the alternatives that satisfies current requirements for universal non-volatile memories. However, the origin of the switching mechanism is still controversial. Here we report the fabrication of a resistive switching device inside a transmission electron microscope, made from a Pt/SiO 2 / a -Ta 2 O 5− x / a -TaO 2− x /Pt structure, which clearly shows reversible bipolar resistive switching behaviour. The current–voltage measurements simultaneously confirm each of the resistance states (set, reset and breakdown). In situ scanning transmission electron microscope experiments verify, at the atomic scale, that the switching effects occur by the formation and annihilation of conducting channels between a top Pt electrode and a TaO 2− x base layer, which consist of nanoscale TaO 1− x filaments. Information on the structure and dimensions of conductive channels observed in situ offers great potential for designing resistive switching devices with the high endurance and large scalability. Despite its importance for non-volatile memory, the origin of resistive switching in a metal insulator-metal structure is unclear. Park et al. fabricate such a structure inside a transmission electron microscope to show that switching occurs via oxygen-vacancy migration, which changes the conduction channels.