In Situ Scanning Transmission Electron Microscopy/Transmission Electron Microscopy Study of Defect-Driven Ag Ion Dynamics and Filament Evolution in CuO Nanowire-Based Memristors

Memristor-based technologies are pivotal for advancing in-memory computing and neuromorphic systems, addressing the von Neumann bottleneck by enabling low-power, high-density data storage. This study investigates the resistive switching (RS) behavior of p-type CuO nanowires (NWs) synthesized via thermal oxidation of a Cu foam integrated with Ag (active) and Au (inert) electrodes. In situ transmission electron microscopy (TEM) and scanning TEM (STEM) reveal the dynamic formation and dissolution of Ag-based conductive filaments under an electrical bias, driven by electrochemical metallization (ECM). The CuO NWs exhibit unique axial planar defects that facilitate Ag⁺ ion migration and nucleation, enhancing RS performance. Electrical measurements demonstrate volatile and nonvolatile switching transitions modulated by compliance current, with asymmetric Ag/CuO NW/Au devices showing diode-like behavior due to Schottky barrier modulation. Conduction mechanisms, including Schottky emission, space-charge-limited current, and Poole-Frenkel emission, are elucidated, transitioning to ohmic conduction in the low-resistance state. These findings provide critical insights into defect-mediated filament dynamics and electrode-dependent RS mechanisms, advancing the development of CuO NW-based memristors for next-generation neuromorphic computing applications.