Diode-less bilayer oxide (WOx–NbOx) device for cross-point resistive memory applications

Abstract

The combination of a threshold switching device and a resistive switching (RS)device was proposed to suppress the undesired sneak current for the integrationof bipolar RS cells in a cross-point array type memory. A simulation for thishybrid-type device shows that the matching of key parameters between switch elementand memory element is an important issue. Based on the threshold switchingoxides, a conceptual structure with a simple metal–oxide 1–oxide 2–metal stackwas provided to accommodate the evolution trend. We show that electroformedW–NbOx–Pt devices can simultaneously exhibit both threshold switching and memory switching.A qualitative model was suggested to elucidate the unique properties in aW–NbOx–Pt stack, where threshold switching is associated with a localized metal–insulator transition in theNbOx bulk, and the bipolar RS derives from a redox at the tip of the localized filament at theWOx–NbOx interface. Such a simple metal–oxide–metal structure, with functionally separated bulk andinterface effects, provides a fabrication advantage for future high-density cross-pointmemory devices.