Local chemical state change in Co-O resistance random access memory

Kelvin probe force microscopy (KFM) and conductive atomic force microscopy (C-AFM) together with micro X-ray photoelectron spectroscopy (XPS) were performed for the stacking structure comprising of the transition metal oxide Co-O and metal electrode, which exhibits large reproducible resistance switching. The application of the external voltage by the C-A,FM cantilever decreases the resistance of Co-O, which accords with the non-polar forming process observed in the Pt/Co-O/Pt trilayer, known as the candidate of resistance random access memory (ReRAM). Furthermore, the KFM and micro XPS experimentally revealed that the local reductive reaction of Co-O possibly nucleates the defect related energy levels which dominates the current conduction in the low resistance state. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.