Growing graphene
25 Oct 2011 by qwbdchbctt.d qwbdchbctt.d
Manchester might be home to graphene’s discovery, but across the pond scientists are working on ways to grow uniform sheets of the wonder material for use in next generation electronics.
Researchers from the University of California – Santa Barbara (UCSB) have refined a method to synthesise high quality graphene in a controlled manner.
“There is no doubt that graphene is a superior material. Intrinsically it is amazing,” said research leader Professor Kaustav Banerjee. “It is up to us, the scientists and engineers, to show how we can use graphene and harness its capabilities.”
Banerjee says the challenge is in how to grow the wonder material, how to transfer or not transfer and pattern it, and how to tailor its properties for specific applications. “But these challenges are fertile ground for exciting research in the future,” he said.
Using low pressure chemical vapour deposition (LPCVD), Banerjee’s team built uniform layers of carbon – as graphene – on a pre-treated copper substrate from methane, which was disintegrated at a specific high temperature. Imperfections in the copper can affect the graphene’s growth, so it must be treated properly and precise selection of the growth parameters allowed quality, uniform graphene to be grown.
The group established a set of techniques that optimised the uniformity and quality of graphene, while controlling the number of graphene layers – from mono-layer to bi-layer graphene – grown on the substrate, an important distinction for future applications in electronics and other technology.
The team are the first to refine the CVD technique to grow high quality graphene. Previous attempts produced low quality graphene in terms of carrier mobility.
“Our graphene exhibits the highest reported field-effects mobility to date for CVD graphene, having an average value of 4000 cm2/V.s with the highest peak value at 5500 cm2/V.s,” said Hong Li, a PhD candidate. “This is an extremely high value compared with the mobility of silicon.”
If graphene can be produced effectively, it may be used in green electronics, super strong material and medical technology. It could also be used in flexible screens and electronic devices, computers and ultra-efficient solar power cells.
