Mimicking Heterosynaptic Plasticity Using 2D Oxide Based Memristors

In this study, we achieve precise thickness controllable oxidation using UV-ozone treatment with different chuck temperatures. With precisely controlled WO_x thickness by UV-ozone treatment, monolithic few-layer WO_x/WSe₂ memristors are fabricated. The postsynaptic responses of the topmost single-layer oxidized WSe₂ and fully oxidized WSe₂ memristors exhibit opposite behaviors, which can be applied to mimic the heterosynaptic plasticity. We explore the feasibility of using each oxidation-layer-controlled memristor as a hardware accelerator by showing pattern recognition rates of 84% and 71% for the 1L and 9L WO_x-based devices, respectively, assessed through CIFAR-10 pattern recognition task. We also examine the applicability of a synaptic cell composed of devices with oppositely switched characteristics. Consequently, the synaptic weight, defined as the difference in conductance between two synaptic devices, can be either increased (potentiated) or decreased (depressed) by simultaneously updating both devices with the same voltage signal. This weight update concept achieves a moderate recognition rate of 85.94% when using an MNIST pattern-based recognition task.