Filament observation in metal-oxide resistive switching devices

Metal-oxide-based resistive random access memory (RRAM) is a predominant candidate for future non-volatile memories. In this Letter, we report on an innovative technique to observe conductive filaments in these oxide-based RRAM devices. We demonstrate the role of these conductive filaments as responsible for the different ON/OFF resistive states in memory devices by means of Conductive Atomic Force Microscopy (C-AFM). More specifically, C-AFM is used to cycle, de-process, and finally characterizes capacitor-like devices. Different conductive filaments are found for the different memory states. As we show, the ON/OFF state of the devices is associated to changes in morphological and electrical properties of the conductive filaments.