Huge field-effect surface charge injection and conductance modulation in metallic thin films by electrochemical gating

TL;DR

This paper demonstrates a novel electrochemical gating method using a polymer electrolyte to inject large surface charges into metallic thin films, significantly modulating their conductance at room temperature.

Contribution

It introduces a new electrochemical gating approach with high charge injection in metallic films, enabling substantial conductance modulation and potential applications in advanced materials.

Findings

Injected surface charge reached 10^15 charges/cm^2

Resistance variations up to 8% in gold films

Results align with a free-electron model for thick films

Abstract

The field-effect technique, popular thanks to its application in common field-effect transistors, is here applied to metallic thin films by using as a dielectric a novel polymer electrolyte solution. The maximum injected surface charge, determined by a suitable modification of a classic method of electrochemistry called double-step chronocoulometry, reached some units in 10^15 charges/cm^2. At room temperature, relative variations of resistance up to 8%, 1.9% and 1.6% were observed in the case of gold, silver and copper, respectively and, if the films are thick enough (> 25 nm), results can be nicely explained within a free-electron model with parallel resistive channels. The huge charge injections achieved make this particular field-effect technique very promising for a vast variety of materials such as unconventional superconductors, graphene and 2D-like materials.