Thermal tuning of dynamic response in Ag-based nanowire networks

TL;DR

This study investigates how thermal and electrical stimuli modify the electrical response of Ag nanowire networks, revealing a transition from resistive to capacitive behavior useful for neuromorphic applications.

Contribution

It demonstrates a method to control the dynamic response of Ag nanowire networks through thermal and electrical stimuli, enabling tunable neuromorphic functionalities.

Findings

Thermal treatment reduces metallic junctions, increasing resistivity.

AC stimuli induce a transition to capacitive response.

Thermal and electrical stimuli enable multiple switching schemes.

Abstract

Self-assembled networks of metallic nanowires (NWs) are being intensively explored as test benches for neuromorphic proposals. In this work, we study the electric transport properties of dense self-assembled networks of Ag-based NWs (AgNWNs) coated with a thin insulating layer, using DC and AC stimuli. The building blocks of this network are the metallic NWs and the NW-NW junctions, either metallic or memristive. In the pristine state, frequency independence of the impedance reveals an over-percolated purely resistive network. A combination of low-temperature annealing and AC stimulus is shown to drastically affect the resistivity of the sample (interpreted as a depopulation of purely metallic junctions), unveiling a rich dynamic response. This procedure triggers the achievement of a capacitive response, which is successfully rationalized using a previously introduced 'two junction model'. Thermal treatment appears to be an indirect strategy to effectively modify the humidity content at the NW-NW intersections and, consequently, enable multiple switching schemes suitable for brain-like processing alternatives.