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Functional Materials for Energy

Cooperative Growth of Large Single-Crystal Graphene Islands


Surface-coverage kinetics, depicting graphene coverage on Cu, reveal two distinct graphene growth mechanisms. Novel methods were developed to reduce nucleation by three orders of magnitude to reveal a regime (red curve) where secondary nucleation is suppressed (compared to blue curve), enabling growth of large, millimeter-scale single-crystalline islands of graphene.

Researchers showed that it is possible to grow large, single-crystal graphene islands by controlling the nucleation density, which determines the growth mechanism. Controlling the synthesis of large, single-crystal grains of graphene and other two-dimensional materials is crucial for many technological applications, as electrical mobility and other important macroscopic properties rely on minimizing boundaries between grains.

Researchers used chemical vapor deposition to grow millimeter-scale, single-crystal islands of graphene. The process selectively incorporated surface carbon at the edges of only a very few graphene islands.  The growth kinetics differ markedly in this mode from typical nucleation-limited growth.  To achieve this growth mode, researchers suppressed island nucleation by more than three orders of magnitude by first reducing the density of nucleation sites on the Cu surface by an oxidation and reduction pretreatment and then employing a transient cooling method during introduction of the hydrocarbon gas. Kinetic modeling demonstrated that selective nucleation initiates a mode that suppresses further nucleation and promotes the growth of a few selected nuclei. This approach is general, allowing for improved synthesis of other two-dimensional layered materials.

Gyula Eres, Murari Regmi, Christopher M. Rouleau, Jihua Chen, Ilia N. Ivanov, Alexander A. Puretzky, and David B. Geohegan, “Cooperative Island Growth of Large-Area Single-Crystal Graphene on Copper Using Chemical Vapor Deposition,” ACS Nano published ASAP online May 15, 2014.  DOI: 10.1021/nn500209d. 

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