Feb 11 2015
Scientists at the University of Groningen have created a breakthrough in producing graphene on an industrial scale without affecting its properties. Graphene has been a "miracle material" when it comes to the manufacture of improved sensors, faster computers and so on. However, producing it on large scale has been a complex task until now.
Graphene consists of a single layer of carbon atoms allowing the passage of electrons without any resistance. The material is the strongest of all metals, and it provides excellent flexibility. Graphene discoverers, Konstantin Novoselov and Andre Geim, fabricated it by peeling graphite using Scotch tape till they isolate a single atomic layer. For this work, they were awarded the Nobel Prize in Physics in 2010.
'The challenge is to find a substrate that not only preserves the properties of graphene, but also enables scalable production.', said Stefano Gottardi, PhD student at the University of Groningen Zernike Institute for Advanced Materials. Chemical vapour deposition is a preferable method. A carbon precursor like methane can be vaporized using heat where the melted precursor reacts with a catalytically active substrate to form graphene on the surface. The substrate used can be a transition metal which also tends to react with the graphene and alters or deteriorates its properties.
The graphene is placed on a non-interacting substrate in order to restore its lost properties. However, the transfer process is very complex and generates defects. A number of scientists, yet, are focussing on the improvement of graphene growth over transition metal substrate such as copper foil substrate.
Supervisors of the Surfaces and Thin Films group of Gottardi, Meike Stöhr and Petra Rudolf also did a similar work. 'When we analyzed a sample of graphene on copper, we made some strange observations', Stöhr said. The observations revealed the formation of copper oxide alongside the copper. However, an excellent graphene film was formed on the copper oxide. These findings proved potentially significant owing to the unaltered properties of graphene upon reaction with oxidized metals.
The Groningen researchers started to study in detail about growing graphene on copper oxide three years ago. The findings along with a detailed characterization of graphene's properties will be published in the journal Nano Letters. In addition, the team claims the valuable finding that graphene grown on copper oxide is decoupled from the substrate, preserving its unique electronic properties.
'Other labs need to reproduce our findings, and quite a bit of work needs to be done to optimize growth conditions,' Stöhr said. When considering the scenario of growing large single-domain crystals of graphene on copper oxide, lithographic techniques can be used to fabricate all types of electronic devices using graphene, on an industrial scale. Thus, an unexpected observation carried out three year ago may open up new platform for the development of next-generation graphene electronics.
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