Self-organized Growth of Graphene Nanomesh with Increased Gas Sensitivity

TL;DR

This paper presents a scalable, low-cost bottom-up CVD method to produce graphene nanomesh with enhanced gas sensitivity, utilizing self-organized silicon nanospheres for patterning and demonstrating improved ammonia detection.

Contribution

The study introduces a novel self-organized process for growing graphene nanomesh using silicon nanospheres, improving gas sensor sensitivity with a scalable and industry-compatible approach.

Findings

2-fold increase in ammonia sensitivity

Successful transfer to various substrates

Nanomesh fabrication is scalable and reusable

Abstract

A bottom-up chemical vapor deposition (CVD) process for the growth of graphene nanomesh films is demonstrated. The process relies on silicon nanospheres to block nucleation sites for graphene CVD on copper substrates. These spheres are formed in a self-organized way through silicon diffusion through a 5 $\mu$m copper layer on a silicon wafer coated with 400 nm of silicon nitride. The temperature during the growth process disintegrates the $Si_3$$N_4$ layer and silicon atoms diffuse to the copper surface, where they form the nanospheres. After graphene nanomesh growth, the Si nanospheres can be removed by a simple hydrofluoric acid etch, leaving holes in the graphene film. The nanomesh films have been successfully transferred to different substrates, including gas sensor test structures, and verified and characterized by Auger, TEM and SEM measurements. Electrical/gas-exposure measurements show a 2-fold increase in ammonia sensitivity compared to plain graphene sensors. This improvement can be explained by a higher adsorption site density (edge sites). This new method for nanopatterned graphene is scalable, inexpensive and can be carried out in standard semiconductor industry equipment. Furthermore, the substrates are reusable.