Two-junction model in different percolation regimes of silver nanowires networks

TL;DR

This paper investigates electrical transport regimes in silver nanowire networks, revealing fuse-type switching in over-percolated systems and proposing a two-junction model to describe their behavior, with implications for neuromorphic computing and transparent electrodes.

Contribution

It introduces a novel two-junction model for different percolation regimes in silver nanowire networks, highlighting fuse-type switching in over-percolated systems for neuromorphic applications.

Findings

High current densities induce fuse-type switching in over-percolated AgNW networks.

Reversible resistive switching enables multiple conductive paths with linear I-V characteristics.

The proposed model accurately describes the observed electrical behavior across regimes.

Abstract

Random networks offer fertile ground for achieving complexity and criticality, both crucial for an unconventional computing paradigm inspired by biological brains' features. In this work, we focus on characterizing and modeling different electrical transport regimes of self-assemblies of silver nanowires (AgNWs). As percolation plays an essential role in such a scenario, we explore a broad range of areal density coverage. Close-to-percolation realizations (usually used to demonstrate neuromorphic computing capabilities) have large pristine resistance and require an electrical activation. Up to now, highly conductive over-percolated systems (commonly used in electrode fabrication technology) have not been thoroughly considered for hardware-based neuromorphic applications, though biological systems exhibit such an extremely high degree of interconnections. Here, we show that high current densities in over-percolated low-resistance AgNW networks induce a fuse-type process, allowing a switching operation. Such electro-fusing discriminates between weak and robust NW-to-NW links and enhances the role of filamentary junctions. Their reversible resistive switching enable different conductive paths exhibiting linear I-V features. We experimentally study both percolation regimes and propose a model comprising two types of junctions that can describe, through numerical simulations, the overall behavior and observed phenomenology. These findings unveil a potential interplay of functionalities of neuromorphic systems and transparent electrodes.