Forming‐Free, Self‐Compliance, Bipolar Multi‐Level Resistive Switching in WO3–x Based MIM Device

Abstract Resistive switching (RS) in metal oxides, which offers self‐compliance and multiple resistance states without the requirement of any high voltage forming step, holds the potential of application in selector less high density resistive random access memory (RRAM) devices. Typically, operation of metal oxide‐based RS devices requires the integration of additional oxide layers or circuit elements to achieve current compliance and complicated device architecture for high‐density memory applications. In this study, a self‐compliance, and multi‐level RS is demonstrated that does not require high voltage forming in a single layer non‐stoichiometric WO 3–x . This study suggests that high oxygen vacancy ( V O ) concentration in the pristine WO 3–x layer leads to its forming‐free filamentary switching characteristics, whereas reversible formation and annihilation of an oxygen‐rich region in the filament at the WO 3–x /Pt junction has been envisaged to be responsible for self‐compliance set and voltage controlled multiple reset resistance states. The results demonstrate non‐stoichiometric WO 3–x with an active metal/oxide interface permeable to reversible oxygen migration can pave the way for producing high density, reliable RRAM devices.