Volume 213, 2019

Interfacial redox processes in memristive devices based on valence change and electrochemical metallization

Abstract

Memristive devices based on electrochemical processes are promising candidates for next-generation memory and neuromorphic applications. The redox processes happening at the interfaces are crucial steps for the ionization as well as generation of counter charges, and are thus indispensable for successful resistive switching, but their detailed mechanism has not been fully clarified. Here, we study the interfacial redox reactions in the forming process of memristive devices based on valence change and electrochemical metallization, using high-resolution electron microscopy and electrostatic force microscopy observations. We show direct evidence for the anodic oxidation of oxygen ions and cathodic reduction of moisture in HfO2- and Ta2O5-based valence change cells, which could take place in different horizontal locations. We further found that the anodic reactions always led to more pronounced structural damage to the electrode, indicating the possibility of additional cathodic reactions without producing gaseous products. When an active electrode is present, oxidation of metal atoms takes place at the anodic interface instead. Further investigations on electrochemical metallization cells have identified Cu ionization and moisture reduction as the anodic and cathodic reactions, respectively, and formation of Cu nuclei at the cathodic interface was directly observed. These findings with microscopic evidence could facilitate future development of memristive devices.

Graphical abstract: Interfacial redox processes in memristive devices based on valence change and electrochemical metallization

Associated articles

Article information

Article type
Paper
Submitted
03 Jun 2018
Accepted
09 Jul 2018
First published
24 Oct 2018

Faraday Discuss., 2019,213, 41-52

Interfacial redox processes in memristive devices based on valence change and electrochemical metallization

K. Liu, L. Qin, X. Zhang, J. Zhu, X. Sun, K. Yang, Y. Cai, Y. Yang and R. Huang, Faraday Discuss., 2019, 213, 41 DOI: 10.1039/C8FD00113H

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