Optimizing TiO₂/HfO₂ Multilayer RRAM for Self-Rectifying Characteristics

Sneak current refers to leakage currents in RRAM crossbar arrays without selector devices, disrupting the accuracy of weighted sum operations in neuromorphic systems, leading to performance degradation and increased power consumption. This study presents a bilayer RRAM structure with a selector layer designed to suppress sneak current in neuromorphic synapse arrays. By utilizing a TiO₂/HfO₂ bilayer structure, it is demonstrated that increasing the thickness of TiO₂ and the work function of the top electrode effectively suppresses current under reverse bias compared to single-layer devices. The bilayer structure achieves rectification levels of 10 to 30 times higher than the single-layer configuration, while increasing the work function of the top electrode yields rectification improvements ranging from 10 to 40 times. This approach enhances the accuracy of synaptic weighted sum operations.