Graphene etching to usher in computing revolution

Move over sticky tape: a spray of zinc atoms followed by a dash of acid is the best way to peel off single layers of graphene, an exotic form of carbon that electrons zip through at a dazzling pace. Such precise control is vital if the material is to be used in super-fast electronic devices.

Stacked layers of carbon atoms arranged in a honeycomb pattern are known as graphite. Separate these into sheets 10 atoms thick or less, and the result is graphene, which has radically different properties. The material was first discovered when Andre Geim and Konstantin Novoselov, both at the University of Manchester, UK, used sticky tape to peel thin layers from a larger lump, earning them a physics Nobel prize.

Now James Tour from Rice University in Houston, Texas, and colleagues have figured out how to remove single layers of graphene from specific locations, a degree of control essential for building electrical components and circuits.

They spray zinc atoms onto a stack of graphene sheets, which only merge with the first layer. Adding acid dissolves the zinc and removes this weakened layer, leaving the rest of the stack intact (Science, DOI: 10.1126/science.1199183). The technique can be used to scrape off a specific number of layers from multi-layer stacks, leaving behind spots that are exactly one, two or three layers thick wherever you want.

The exact number defines graphene's properties: a single layer behaves like a metal, and could form a wire, whereas a double layer is like a semiconductor and could be built into a transistor. "You could build a series of devices very close to each other in any pattern, just by removing portions of each layer," says Tour.

A way to etch graphene more precisely in the horizontal direction is the next step, says Zakaria Moktadir, a nano-scientist at the University of Southampton, UK.