Optimized Programming Scheme Enabling Linear Potentiation in Filamentary HfO2 RRAM Synapse for Neuromorphic Systems

In this brief, we demonstrate the multilevel cell (MLC) characteristics of an HfO2-based resistive memory (RRAM) array as a synaptic element for neuromorphic systems. We utilize various programming schemes to linearly change the resistance state with either set voltage/pulse ramping or gate voltage ramping. Our results reveal that the MLC relates to the size of the conductive filament involved in the movement of oxygen vacancies with respect to applying pulses. Thus, by optimizing the pulse for a set condition, such as an identical pulse, we achieve linearly increased MLC behavior, thereby enabling a high accuracy for pattern recognition in neuromorphic systems.