Molecular Understanding of the Effect of Hydrogen on Graphene Growth by Plasma-Enhanced Chemical Vapor Deposition

TL;DR

This study uses molecular dynamics simulations to explore how hydrogen influences graphene growth during plasma-enhanced chemical vapor deposition, revealing optimal conditions for high-quality graphene formation.

Contribution

The paper provides a detailed atomic-scale understanding of hydrogen's role in PECVD graphene growth, highlighting the impact of precursor composition on quality and growth rate.

Findings

Optimal C/H ratio of 1:1 yields the most hexagonal rings.

Higher hydrogen content reduces growth rate.

Hydrogen prevents curved carbon structures.

Abstract

Plasma-enhanced chemical vapor deposition (PECVD) provides a low-temperature, highly-efficient, and catalyst-free route to fabricate graphene materials by virtue of the unique properties of plasma. In this paper, we conduct reactive molecular dynamics simulations to theoretically study the detailed growth process of graphene by PECVD at the atomic scale. Hydrocarbon radicals with different carbon/hydrogen (C/H) ratios are employed as dissociated precursors in the plasma environment during the growth process. The simulation results show that hydrogen content in the precursors significantly affects the growth behavior and critical properties of graphene. The highest number of hexagonal carbon rings formed in the graphene sheets, which is an indicator of their quality, is achieved for a C/H ratio of 1:1 in the precursors. Moreover, increasing the content of hydrogen in the precursors is shown to reduce the growth rate of carbon clusters, and prevent the formation of curved carbon structures during the growth process. The findings provide a detailed understanding of the fundamental mechanisms regarding the effects of hydrogen on the growth of graphene in a PECVD process.