Evidence of electrochemical resistive switching in the hydrated alumina layers of Cu/CuTCNQ/(native AlOx)/Al junctions

• Published in: Journal of applied physics 2013-09, Vol.114 (12)
• Main Authors: Knorr, Nikolaus, Bamedi, Ameneh, Karipidou, Zoi, Wirtz, René, Sarpasan, Mustafa, Rosselli, Silvia, Nelles, Gabriele
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4823851

We have investigated bipolar resistive switching of Cu/CuTCNQ/Al cross-junctions in both vacuum and different gas environments. While the generally observed S-shaped I-V hysteresis was reproduced in ambient air, it was reversibly suppressed in well-degassed samples in vacuum and in dry N2. The OFF-switching currents in ambient air peaked when approximately +2.6 V was applied to the Al electrode at low voltage sweep rates. OFF-switching at constant bias was accelerated in humid and oxygen-rich atmospheres. For unbiased samples stored in air, ON-state (RON) and OFF-state (ROFF) resistances increased with time, and RON surpassed the initial ROFF after approximately one week. Retention times were enhanced for samples stored in vacuum and those with a larger cross-junction area. We suggest that resistive switching occurs in a hydrated native alumina layer at the CuTCNQ/Al interface that grows in thickness during exposure to ambient humidity: ON-switching by electrochemical metallization of free Al and/or Cu ions and OFF-switching by anodic oxidation of the Al electrode and previously grown metal filaments.