Methane as an effective hydrogen source for single-layer graphene synthesis on Cu foil by plasma enhanced chemical vapor deposition

TL;DR

This study demonstrates that methane alone can serve as an effective hydrogen source for synthesizing high-quality single-layer graphene on copper foil using plasma-enhanced chemical vapor deposition, with plasma power controlling hydrogen availability.

Contribution

It shows that hydrogen species generated from methane decomposition during PECVD can replace explicit H2 flow for graphene growth, with plasma power tuning hydrogen partial pressures.

Findings

Maximum grain size at 50 W plasma power

Hydrogen partial pressures are controlled by plasma power

High-quality graphene achieved without external H2 flow

Abstract

A single-layer graphene is synthesized on Cu foil in the absence of H2 flow by plasma enhanced chemical vapor deposition (PECVD). In lieu of an explicit H2 flow, hydrogen species are produced during methane decomposition process into their active species (CHx<4), assisted by the plasma. Notably, the early stage of growth depends strongly on the plasma power. The resulting grain size (the nucleation density) has a maximum (minimum) at 50 W and saturates when the plasma power is higher than 120 W because hydrogen partial pressures are effectively tuned by a simple control of the plasma power. Raman spectroscopy and transport measurements show that decomposed methane alone can provide sufficient amount of hydrogen species for high-quality graphene synthesis by PECVD.