First-Principles Thermodynamics of Graphene Growth on Cu Surface

TL;DR

This study uses first-principles calculations and thermodynamics to analyze graphene growth on copper, revealing that CHx species are the active growth agents rather than atomic carbon, which explains experimental behaviors.

Contribution

It introduces a new thermodynamic perspective showing that CHx, not atomic carbon, drives graphene growth on Cu, improving understanding and guiding quality enhancement.

Findings

Carbon atoms are thermodynamically unfavorable on Cu surface.

CHx species are the main active agents for graphene growth.

The new model explains experimental nucleation behaviors.

Abstract

Chemical vapor deposition (CVD) is an important method to synthesis grapheme on a substract. Recently, Cu becomes the most popular CVD substrate for graphene growth. Here, we combine electronic structure calculation, molecular dynamics simulation, and thermodynamics analysis to study the graphene growth process on Cu surface. As a fundamentally important but previously overlooked fact, we find that carbon atoms are thermodynamically unfavorable on Cu surface under typical experimental conditions. The active species for graphene growth should thus mainly be CHx instead of atomic carbon. Based on this new picture, the nucleation behavior can be understood, which explains many experimental observations and also provides us a guide to improve graphene sample quality.