Facile and Ultraclean Graphene-on-Glass Nanopores by Controlled Electrochemical Etching

TL;DR

This paper presents a simple electrochemical method to create ultra-clean graphene nanopores on glass, achieving low electrical noise and enabling improved single-molecule sensing applications.

Contribution

It introduces a controlled electrochemical etching technique for fabricating clean graphene nanopores on glass substrates with significantly reduced noise.

Findings

Graphene nanopores fabricated with electrochemical etching show low electrical noise.

GOG nanopores exhibit an order-of-magnitude lower broadband noise than TEM-drilled pores.

DNA translocation experiments confirm the functionality and low noise of the nanopores.

Abstract

A wide range of approaches have been explored to meet the challenges of graphene nanostructure fabrication, all requiring complex and high-end nanofabrication platform and suffering from surface contaminations, potentially giving electrical noise and increasing the thickness of the atomically thin graphene membrane. Here, with the use of an electrical pulse on a low capacitance graphene-on-glass (GOG) membrane, we fabricated clean graphene nanopores on commercially available glass substrates with exceptionally low electrical noise. In situ liquid AFM studies and electrochemical measurements revealed that both graphene nanopore nucleation and growth stem from the electrochemical attack on carbon atoms at defect sites, ensuring the creation of a graphene nanopore. Strikingly, compared to conventional TEM drilled graphene nanopores on SiN supporting membranes, GOG nanopores featured an order-of-magnitude reduced broadband noise, which we ascribed to the electrochemical refreshing of graphene nanopore on mechanically stable glass chips with negligible parasitic capacitance (1 pF). Further experiments on double-stranded DNA translocations demonstrated a greatly reduced current noise, and also confirmed the activation of single nanopores. Therefore, the exceptionally low noise and ease of fabrication will facilitate the understanding of the fundamental property and the application of such atomically thin nanopore sensors.