Graphene shaping technique to allow for highly-efficient nanocircuits

A method that allows for microscopic shaping of graphene into electronic circuits could revolutionise the industry according to researchers.

The team, formed from professors at the University of Wisconsin (UW) and the U.S. Department of Energy's Argonne National Laboratory, found that they could control the growth paths of graphene nanoribbons on the surface of a germanium crystal.

Germanium is a semiconductor and the new technique provides a straightforward way to make semiconducting nanoscale circuits from graphene.

Graphene is a one-atom-thick, two-dimensional sheet of carbon atoms that can move electrons at a faster rate than any other material across its surface without interference. This high mobility makes the material an ideal candidate for faster, more energy-efficient electronics.

UW researchers used chemical vapour deposition to grow graphene nanoribbons on germanium crystals.

This technique uses methane which decomposes at high temperatures into carbon atoms (graphene) that settle onto the germanium's surface to form a uniform graphene sheet. The researchers found they could exert very precise control over the material which is needed to form complex circuits.

"Some researchers have wanted to make transistors out of carbon nanotubes but the problem is that they grow in all sorts of directions," said Brian Kiraly of Argonne.

"The innovation here is that you can grow these along circuit paths that works for your tech."

Michael Arnold, a professor on the UW team, said that graphene naturally forms smooth nanoribbons shapes when grown on germanium.

"The widths can be very, very narrow and the lengths of the ribbons can be very long, so all the desirable features we want in graphene nanoribbons are happening automatically with this technique," he said.

The researchers used a scanning tunnelling microscope that uses electrons (instead of light or the eyes) to see the characteristics of a sample to confirm the presence of graphene nanoribbons growing on the germanium.

Data gathered from the electron signatures allowed the researchers to create images of the material's dimensions and orientation and determine how electrons scattered throughout the material.

Last month, Canadian researchers developed superconducting graphene by using a lithium atom coating.

A recently discovered graphene production method could also pave the way for wider commercialisation of the material and allow for flexible electronics.