Unipolar resistive switching with forming-free and self-rectifying effects in Cu/HfO2/n-Si devices

One of the most effective methods integrating self-rectifying RRAM is alleviating sneak current in crossbar architecture. In this work, to investigate RRAMs with excellent properties of self-rectifying effect, simple Cu/HfO2/n-Si tri-layer devices are fabricated and investigated through I − V characteristic measurement. The experimental results demonstrate that the device exhibits forming-free behavior and a remarkable rectifying effect in low resistance state (LRS) with rectification ratio of 104 at ±1 V, as well as considerable OFF/ON ratio (resistive switching window) of 104 at 1 V. The formation and annihilation of localized Cu conductive filament plays a key role in the resistive switching between low resistance state (LRS) and high resistance state (HRS). In addition, intrinsic rectifying effect in LRS attributes to the Schottky contact between Cu filament and n-Si electrode. Furthermore, satisfactory switching uniformity of cycles and devices is observed. As indicated by the results, Cu/HfO2/n-Si devices have a high potential for high-density storage practical application due to its excellent properties.