Resistive switching in silicon suboxide films

International audienceWe report a study of resistive switching in a silicon-based memristor/resistive RAM (RRAM)device in which the active layer is silicon-rich silica. The resistive switching phenomenon is anintrinsic property of the silicon-rich oxide layer and does not depend on the diffusion of metallicions to form conductive paths. In contrast to other work in the literature, switching occurs inambient conditions, and is not limited to the surface of the active material. We propose a switchingmechanism driven by competing field-driven formation and current-driven destruction offilamentary conductive pathways. We demonstrate that conduction is dominated by trap assistedtunneling through noncontinuous conduction paths consisting of silicon nanoinclusions in a highlynonstoichiometric suboxide phase. We hypothesize that such nanoinclusions nucleate preferentiallyat internal grain boundaries in nanostructured films. Switching exhibits the pinched hysteresis I/Vloop characteristic of memristive systems, and on/off resistance ratios of 104:1 or higher can beeasily achieved. Scanning tunneling microscopy suggests that switchable conductive pathways are10 nm in diameter or smaller. Programming currents can be as low as 2 lA, and transition timesare on the nanosecond scale