Transition from Reaction- to Diffusion-Limited Growth of Graphene by Chemical Vapor Deposition

Abstract

Recently, monolayer domain growth has been observed in real time by focusing the radiation emitted from graphene; the method is termed radiation-mode optical microscopy (Rad-OM). By Rad-OM, the incorporation of precursors to graphene rather than the formation of precursors was considered most likely to be the rate-determining factor in the chemical vapor deposition growth of graphene. Here, we scrutinize the observed domain growth and show that the domain growth is decelerated after a certain time period because the rate-determining factor changes from (incorporation) reaction-limited to diffusion-limited as the domain size increases. The transition to the diffusion-limited growth could be caused either by the increase of the periphery length of single domain or by the interference of the diffusion fields from adjacent domains. The distinction between two mechanisms is difficult owing to the similar time-dependence and the long-range nature of the interference of the diffusion fields. Nevertheless, the lower bound of the incorporation velocity into the domain and the upper bound of the desorption rate constant of precursors from the substrate could be estimated by Rad-OM.

Operando Characterization and Molecular Simulations Reveal the Growth Kinetics of Graphene on Liquid Copper During Chemical Vapor Deposition

“…The fact that R eff increases at a constant rate across a wide range of flake sizes (ranging from 15 μm up to 1.6 mm in diameter) suggests that growth takes place in an attachment-limited (also called reaction- or edge-kinetics-limited) regime. According to theoretical models for constant flake shapes, − the radial growth rates in this regime are proportional to both the extent of the bare Cu surface and the concentration of the reactant. Since we find equivalent growth rates of flakes with equivalent R eff but different shapes, there may be a cancelation between faster-growing areas and slower-growing areas in the case of the noncompact shapes so that the effective radius stays shape-independent.…”