Improved Synaptic Behavior Under Identical Pulses Using AlO_{<italic>x</italic>}/HfO₂Bilayer RRAM Array for Neuromorphic Systems

TLDR

The study analyzes how identical pulses on filamentary RRAM can implement synaptic functions in neuromorphic systems. We demonstrate linear potentiation/depression of conductance under identical pulses by leveraging a barrier layer in an AlO_x/HfO₂ bilayer RRAM fabricated on an Al electrode. The device achieves multilevel conductance states, but abrupt set switching can degrade pattern‑recognition accuracy; however, by symmetrically controlling the conductance range at both polarities, the RRAM yields significantly improved accuracy in neural‑network pattern recognition.

Abstract

We analyze the response of identical pulses on a filamentary resistive memory (RRAM) to implement the synapse function in neuromorphic systems. Our findings show that the multilevel states of conductance are achieved by varying the measurement conditions related to the formation and rupture of a conductive filament. Furthermore, abrupt set switching behavior in the RRAM leads to an unchanged conductance state, leading to degradation in the accuracy of pattern recognition. Thus, we demonstrate a linear potentiation (or depression) behavior of conductance under identical pulses using the effect of barrier layer on the switching, which was realized by fabricating an RRAM on top of an Al electrode. As a result, when the range of the conductance is symmetrically controlled at both polarities, a significantly improved accuracy is achieved for pattern recognition using a neural network with a multilayer perceptron.