Nonlinear Switching With Ultralow Reset Power in Graphene-Insulator-Graphene Forming-Free Resistive Memories

A high-performance resistive random access memory with graphene top and bottom electrodes and TiO_x/Al₂O₃/TiO₂ dielectric stacks is reported. The devices exhibit forming-free switching with stable operation at sub-μA operating current. The switching is highly nonlinear with rectifying characteristics in the sub-μA regime. As a result, the reset current is orders of magnitude smaller than the current compliance. Due to the increasing nonlinearity with decreasing current compliance, the reset current is ~100 pA or less for the current compliance of 180 nA. Overall, the devices demonstrate sub-μA operating current, sub-nW reset power, ON/OFF ratio of ~10⁴, stable dc endurance for more than 200 dc cycles, and stable retention up to 10⁴ s. The rectifying characteristic offers potential to reduce sneak-currents in cross-bar architectures.