Growing graphene

A material that could replace silicon and lead to higher-speed electronics has for the first time been produced to a size and quality where it can be practically developed.

A collaborative European research project produced the material — known as graphene —to the size of a small coin. Its quality as an electrically conductive device was confirmed by the UK’s National Physical Laboratory (NPL) Quantum Detection Group in Teddington.

Scientists have been interested in the unique properties of graphene since it was first discovered at Manchester University five years ago.

$59m The amount the market for graphene is expected to be worth by 2015 Source: Lux Research

Derived from graphite, the material is stronger and possesses greater electrical conductivity than other semiconductor materials such as silicon or gallium arsenide.

JT Janssen, an NPL fellow who worked on the project, explained that producing graphene into any viable size has been a bugbear of the scientific community for the past half decade.

‘When the material was discovered five years ago in Manchester University, they actually peeled individual layers from the graphite with a technique that used sticky tape,’ he said.

Janssen added that the researchers at Manchester used this technique to produce thin slivers of individual graphene layers measuring only one atom thick. ‘However, it was not an industrial process. You can’t sit in a factory and peel graphene off with sticky tape.’

Scientists have since been developing techniques to grow graphene like other semiconducting materials, but with little success until now.

The recent graphene sample was grown at Sweden’s Linköping University, which was one of four universities involved with the research project.

Janssen said the sample was developed by heating silicon carbide to a high enough temperature for the silicon to diffuse away. ‘You’re then left with a layer of carbon that forms the graphene,’ he added.

NPL measured the graphene for Quantum Hall Effect, which looks at the freedom of the electrons and the carrier density within the material.

Janssen said his group found the graphene sample had much higher mobility at room temperature compared with silicon or gallium arsenide.

However, he does not believe graphene is ready to fully replace silicon yet.

He explained graphene is unlikely to be used for whole computer chips any time soon. Instead, he said, it will be used for making critical parts of computer chips and those parts would be integrated with silicon.

This is a tricky engineering process, but it could be demonstrated within a year.

Graphene is currently suitable for use in metrology as a resistance standard, but its use as an electronics component for consumer goods is likely to be five years away.

Other participants in the research programme included Chalmers University of Technology in Göteborg, Sweden; Politecnico di Milano in Italy; and Lancaster University in the UK.