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

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 the methane decomposition process into their active species (CH_x<4), assisted with 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 a sufficient amount of hydrogen species for high-quality graphene synthesis by PECVD.