Bipolar resistance switching in Pt/CuO x /Pt via local electrochemical reduction

• Published in: Applied physics letters 2014-06, Vol.104 (24)
• Main Authors: D'Aquila, Kenneth, Phatak, Charudatta, Holt, Martin V., Stripe, Benjamin D., Tong, Sheng, Park, Woon Ik, Hong, Seungbum, Petford-Long, Amanda K.
• Format: Article
• Language: English
• Subjects: MATERIALS SCIENCE
• ISSN: 0003-6951; 1077-3118

We investigated the local changes in copper oxidation state and the corresponding resistance changes in Pt/CuOx/Pt nanoscale heterostructures using x-ray nanoprobe spectro-microscopy and current-voltage characterization. After gentle electroforming, during which the current-voltage behavior remains non-linear, the low resistance state was reached, and we also observed regions of 160 nm width that show an increase in Cu K-alpha fluorescence intensity, indicative of partial reduction of the CuOx. Analysis of the current voltage curves showed that the dominant conduction mechanism is Schottky emission and that the resistance state is correlated with the Schottky barrier height. We also propose that the reversible resistivity change in these Pt/CuOx/Pt heterostructures occurs through local electrochemical reduction leading to change of the Schottky barrier height at the interface between Pt and the reduced CuOx layers and to change of the CuOx resistivity within laterally confined portions of the CuOx layer. Our experiments reveal important insights into the mechanism of resistance switching of Pt/CuOx/Pt performed in a current and voltage regime that does not create a metallic conduction path.