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

## TL;DR

This study uses electron microscopy to observe how defects in CuO nanowires influence the movement of Ag ions and the formation of conductive filaments in memristors.

## Contribution

The study reveals defect-driven Ag ion dynamics and filament evolution in CuO nanowire memristors using in situ TEM/STEM.

## Key findings

- Axial planar defects in CuO nanowires enhance Ag+ ion migration and filament formation.
- Electrical measurements show volatile and nonvolatile switching modulated by compliance current.
- Conduction mechanisms transition to ohmic behavior in the low-resistance state.

## Abstract

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.