Evolution of graphene growth on Cu and Ni studied by carbon isotope labeling

TL;DR

This study uses carbon isotope labeling to clarify the growth mechanisms of graphene on Cu and Ni, revealing surface adsorption on Cu and segregation-precipitation on Ni, which informs better manufacturing processes.

Contribution

It provides definitive experimental evidence distinguishing graphene growth mechanisms on Cu and Ni using isotope labeling.

Findings

Graphene on Cu grows via surface adsorption.

Graphene on Ni grows via segregation-precipitation.

Surface adsorption is a self-limiting and manufacturable growth process.

Abstract

Large-area graphene is a new material with properties that make it desirable for advanced scaled electronic devices1. Recently, chemical vapor deposition (CVD) of graphene and few-layer graphene using hydrocarbons on metal substrates such as Ni and Cu has shown to be a promising technique2-5. It has been proposed in recent publications that graphene growth on Ni occurs by C segregation2 or precipitation3, while that on Cu is by surface adsorption5. In this letter, we used a carbon isotope labeling technique to elucidate the growth kinetics and unambiguously demonstrate that graphene growth on Cu is by surface adsorption whereas on Ni is by segregation-precipitation. An understanding of the evolution of graphene growth and thus growth mechanism(s) is desired to obtain uniform graphene films. The results presented in this letter clearly demonstrate that surface adsorption is preferred over precipitation to grow graphene because it is a self-limiting process and thus manufacturable.