Self-rectifying Ag2O1-δ-based synaptic crossbar array for neuromorphic computing applications
摘要
Self-rectifying memristors can significantly suppress the sneak current and lead to the development of a highly dense, power and area-efficient passive crossbar array, facilitating parallel analog computation in neuromorphic computing systems. This study reports a selector-less, forming-free Ag2O1-δ-based 64 × 64 (4 kb) passive memristive crossbar array. The fabricated memristive cells exhibit self-rectifying (rectification ratio >103) analog bipolar switching characteristics with negligible spatiotemporal variations. Multilevel (>4-bit) conductance states (~3.60 μS to ~22.30 μS at 373 K) were achieved through controlled compliance current (20 μA ≤ ICC ≤ 1 mA). Based on the robust synaptic characteristics of the memristors assessed by the excitatory/inhibitory electrical signals, the applicability of the crossbar array was simulated via a multi-layer perceptron (MLP) model on the MNIST dataset, achieving 96.08% recognition accuracy under the device constraints. To further enable accurate and noise-robust convolutional neural network (CNN) deployment on memristor hardware, three training strategies such as Post-Training-Quantisation, Straight-Through-Estimator, and Alpha-Blending were evaluated. Alpha-Blending emerged as the most effective and robust strategy, enabling a ResNet-18 model to achieve an accuracy of 94.08% on the CIFAR-10 task and 75.28% on the CIFAR-100 task, with drops of only 1.07% and 3.2%, respectively, under moderate levels of additive Gaussian noise (σ = 0.10).