A sheaf of papers on #graphene

It is impossible to keep up with the torrent of papers on our wonder material. So let's just look at a few from the past few days.

How to make vertically oriented graphene nanosheets

The journal Nanoscale has just published a paper, a review article no less, with the title “Plasma-enhanced chemical vapor deposition synthesis of vertically oriented graphene nanosheets”.  All behind a paywall, of course.

The abstract gives a good idea of what you will get if you cough up your £36. “This paper attempts to summarize the state-of-the-art research on [plasma-enhanced chemical vapour deposition] growth of [vertically oriented graphene] nanosheets to provide guidelines on the design of plasma sources and operation parameters, and to offer a perspective on outstanding challenges that need to be overcome to enable commercial applications of VG.”

It comes with an interesting picture:

Pity there isn’t a caption. Guess you have to buy the paper for that.

More in Nanoscale

Nanoscale also bills several other graphene papers in the same issue:

Graphene plasmon enhanced photoluminescence in ZnO microwires

Atomistic modelling of CVD synthesis of carbon nanotubes and graphene

Self-assembled graphene quantum dots induced by cytochrome c: A novel biosensor for trypsin with remarkable fluorescence enhancement

Another paper turns up in the journal's roster of This week’s HOT articles

Mechanical reinforcement fibers produced by gel-spinning of poly-acrylic acid (PAA) and graphene oxide (GO) composites 

In theory

Nice to see the theoreticians are on the case. This in Phys. Rev. Lett. from folks at the Institute for Theoretical Physics at the University of Regensburg.

Spin-Orbit Coupling in Hydrogenated Graphene offers “First-principles calculations of the spin-orbit coupling in graphene with hydrogen adatoms in dense and dilute limits”. So now you know.

Laser peels off graphene layers

Thanks to the excellent regime over at IoP Publishing, everyone has 30 days in which to grab the paper Thinning of large-area graphene film from multilayer to bilayer with a low-power CO2 laser from the journal Nanotechnology, a constant source of new papers on graphene. The abstract tells us that “Bilayer graphene has attracted a great deal of attention for many electronic and optical applications”.

This paper describes a way of turning the multilayer graphene you get when you make graphene with chemical vapour deposition into a ‘bilayer’ material. This isn’t the first time that people have used layers to thin down graphene, but this time, the researchers claim, the approach “enables high-efficiency thinning of large-area graphene film whilst using a significantly reduced power density and an increased laser beam diameter”.

There’s an interesting connection to Manchester University. This time it isn’t the world famous graphene group that chipped in, but the Laser Processing Research Centre. The graphene expertise seems to have come from Tsinghua University in Beijing.

Graphene on silicon

Another interesting paper over at IoPP is in the open access publication New Journal of Physics, so no need to rush for this one. Strongly confined gap plasmon modes in graphene sandwiches and graphene-on-silicon comes from Imperial College. The researchers have been slapping payers of graphene on top of one another, or, as they put it, “two infinitely long graphene ribbons vertically offset by a gap”.

To demonstrate the relevance of their work, the authors report “an unprecedented level of confinement of a terahertz wave of nearly five orders of magnitude when a graphene ribbon is placed on top of a highly doped silicon substrate”. They add that these phenomena and semiconducting substrates “could be the building blocks for both graphene-based integrated optics and ultrasensitive sensing modalities”. Now it just needs someone to do the experiments to show that this is not a mad idea.

Spintronics doctors and other graphene stories

The week started well for graphene. No less an accolade than a paper in the Proceedings of the National Academy of Sciences. The trouble comes when you try to make head or tail of the title, Valley Chern numbers and boundary modes in gapped bilayer graphene. It seems to be something to do with topological states and defects.

The researchers at the University of Pennsylvania and the University of Texas at Austin conclude that “gapless interface modes at a LSW are topologically stable when the potential difference between layers is the dominant energy scale and the valley index can be regarded as a good quantum number”. Doubtless this is a truly significant finding for some folks, or it wouldn’t have got into the PNAS. Sadly, the journal does not deem it important enough to have written one of its reader friendly briefs.

Graphene meets silicon

There doesn’t seem to have been much recent graphene activity in Norway, so it is interesting to see a press release on “potential products from the union of semiconductors and graphene”. As the release from The Research Council of Norway puts it “Semiconductors grown on graphene at the Norwegian University of Science and Technology (NTNU) may be the most important research breakthrough of 2012 in Norway.”

The release also has an interesting historical anecdote. It seems that the NNTU was put on to the case of graphene six months before the material collected a Nobel prize for its ‘inventors’ and “before graphene had become an item of interest”.  A South Korean post-doctoral fellow Dong Chul Kim at NTNU suggested to Helge Weman and Bjørn-Ove Fimland “that they should take a closer look at precisely this material”. The researchers had already grown gallium arsenide nanowires on silicon substrates, so they looked into the possibility of growing semiconductor nanowires on graphene instead. You can follow how they did it in a video on YouTube.

Grow your own nanowires on graphene

The Norwegian researchers aren’t blind to the potential of their work. As they said when they first touted their breakthrough, patented of course, they have set up a business, CrayoNano to turn the science into money.

Manchester untied

They are at it again in the labs that brought us graphene. According to the latest press release “a University of Manchester team led by Dr Irina Grigorieva shows how to create elementary magnetic moments in graphene and then switch them on and off”. The report is another part of the armoury of graphene electronics.

The news, trailing a paper in Nature Communications, comes with some entertaining notions “Graphene is a chicken wire made of carbon atoms.” On a more scientific note, it quotes Dr Rahul Nair, who led the experimental effort: “Graphene already attracts interest in terms of spintronics applications, and I hope that the latest discovery will make it a frontrunner.”

The media friendly quotes may owe something to the fact that the Manchester team now seems to have a full time communications person. The contact for the story is Daniel Cochlin who is billed as Graphene Communications and Marketing Manager.

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