Researchers Have Found a Way to Make Wafer-Sized Graphene with Good Electrical Graphene

Researchers at the University of Oxford have found a way to make wafer-sized graphene with good electrical characteristics.

Grown on copper using chemical vapour deposition (CVD), the material is not mono-crystalline, but crystal alignment is good across grain boundaries allowing electrons to cross with less disturbance than between randomly-orientated graphene domains.

"We found out that there is a strong correlation between copper grain orientation and the orientation of the graphene. By knowing this, we can get all graphene domains aligned. We still get grain boundaries, but they are fewer and neater," Professor Nicole Grobert told Electronics Weekly.

The best quality graphene is still pulled in flakes a few mm across from lumps of natural graphite using sticky tape.

"We are getting closer to graphite graphene, the limitation is the quality of the copper. And our graphene is certainly bigger, we could grow or A4 bigger, said Grobert.

Electronic properties of graphene

Ideally, graphene for electronics would be grown on an insulating substrate and used in-situ - the amazing electronic properties of graphene are swamped by metal substrates.

However, certain metals aid deposition - making the growing of reasonable graphene possible - so metal-grown graphene is transferred to an insulating substrate, and the metal dissolved away.

"People have used copper as a base material before, but this is the first time anyone has shown that the many different types of copper surfaces can indeed strongly control the structure of graphene," said Grobert, adding that if graphene has to be transferred, it might as well be better-quality graphene with neat grain alignment.

Hexagonal graphene domains are well-aligned - SEM image

"This is an important step towards finding a way of manufacturing graphene in a controlled fashion at an industrial scale, something that is essential if we are to bridge the gap between fundamental research and building useful graphene-based technologies," said Grobert.

The Oxford-led team, includes researchers from Forschungszentrum Juelich Germany, the University of Ioannina Greece, and company Renishaw.

A report on the material, which is two-atom-thick graphene, is to be published in the journal ACS Nano as "Controlling the orientation, edge geometry, and thickness of chemical vapour deposition graphene".

Graphene domains formed across copper grain boundaries - optical photo. Rectangles are graphene domains, black lines are copper grain boundaries