Credit: © 2009 NPG

Working with graphene has always required a trade-off. On the one hand was the desire for large areas on arbitrary substrates, and on the other hand was the maintenance of the perfect two-dimensional crystal structure that makes graphene attractive in the first place. This trade-off was because known methods for producing and transferring large areas of graphene involved harsh chemical or mechanical processing.

Now, Byung Hee Hong of Sungkyunkwan University and colleagues1 in Korea and the United States have succeeded in making large (square centimetre) areas of graphene that preserve much of its pristine structure. Their approach is to flow gaseous carbon over a thin, heated nickel surface, cool the nickel quickly and then gently etch it away. The resulting films represent a step towards the convergence of a very useful set of properties: charge mobility, optical transparency, mechanical resilience and the ability to pattern. The future use of graphene, whether as an active semiconductor or simply as a contact, will probably rely on most of these.

A strictly two-dimensional crystal was thought to be physically impossible as little as five years ago. This latest research has produced single- or few-layer two-dimensional graphene crystals with an aspect ratio greater than 107.