Effect of controlled humidity on resistive switching of multilayer VO2 devices

Abstract

Resistive switching in lateral devices using vanadium oxide sheets is reported. The devices undergo an electric field induced insulator-to-metal transition (E-IMT). A sudden jump in the current level up to two orders in magnitude at a defined bias voltage and linearly increasing with a further increase in the bias voltage is observed. Further, the devices also show up multi-step sequential breakdown. The relative change in the resistance from high resistance state (HRS) to low resistance states (LRS) during the resistive switching is up to 700. The breakdown voltage and the switching characteristics of the devices strongly depend on the relative humidity. By varying relative humidity controllably from 11% to 95%, the robustness of the switching device is studied. Clear hysteresis in the switching cycles is shown (current–voltage characteristics) at various humidity levels at room temperature. The threshold voltage reduces exponentially with humidity. This dependence of switching voltage with humidity is attributed to the dissociation of water molecules on the VO2 surface. The water molecule donates charge carriers to the VO2 by dissociating on the surface resulting in two hydroxyl ions on the surface in combination with oxygen defect available on the VO2 surface.