Transition Between Digital Switching and Analog Synapse in AgO_x/SnSe₂ Memristor Through Thickness Engineering

Inspired by biological synapses, memristors are regarded as key components for overcoming the limitations of traditional von Neumann architectures. A major challenge lies in achieving controllable switching between digital and analog functionalities within the same device. In this work, we demonstrate an AgO_x/SnSe₂-based memristor in which digital and analog switching behaviors can be modulated by adjusting the AgO_x layer thickness. The device is fabricated through moderate-temperature thermal oxidation, and the switching transition is likely related to oxygen-vacancy filament evolution influenced by AgO_x thickness. In the digital switching mode, when AgO_x layer is thick (75 nm), the device exhibits an abrupt switching characteristic with a high ON/OFF ratio exceeding 10⁶, ultra-low subthreshold swing below 10 mV dec^-1, 5000 s retention, and air stability under tested conditions. In contrast, with a thinner AgO_x layer (35 nm), the device shows a gradual resistive switching process, indicative of analog synapse behavior, which could enable synaptic weight modulation and signal recognition, such as electrocardiogram (ECG) signals, within the measured conditions. This work presents a facile thickness engineering strategy for digital-to-analog tuning behaviors and underscores the potential of silver oxide-based memristors for multifunctional memory and neuromorphic computing.