The 2010 Nobel Prize in Physics has been awarded to the two researchers who performed the first experiments on graphene, a two-dimensional sheet of carbon atoms. The award, given to University of Manchester physicists Andre Geim and Konstantin Novoselov, recognizes work that began less than a decade ago on a material that’s since been used to make record-breaking transistors and stretchy electrodes.
Graphene is a material of many superlatives: it’s the best conductor of electricity at room temperature and the strongest material ever tested. It’s also an excellent heat conductor, and is transparent and flexible. Before Geim and Novoselov’s work, researchers had theorized the material’s existence, and had predicted that it could be used to make transistors more than 100 times faster than those in today’s silicon-based chips. But until the U.K. researchers made and tested graphene in 2004, many physicists guessed that materials one-atom thick would be unstable.
In 2004, Geim and Novoselov made graphene in the lab by using adhesive tape to peel a chunk of graphite into ever-thinner sheets, as in this video. A graphene sheet is a single layer of carbon atoms enmeshed in a honeycomb-like, repeating hexagon pattern.
Graphene is a naturally occurring material. Layers of graphene make up the graphite found in pencil lead. When you trace a pencil on a piece of paper, these layers are cleaved, leaving thin layers of these carbon sheets. By crushing graphite and peeling it with tape into ever-thinner flakes and eventually into pieces just one atom thick, Geim and Novoselov were able to make usuable quantities of graphene that could be studied and to lay to rest doubts about graphene’s stability.
In their initial work, in 2004, they not only demonstrated that they had made graphene, but also elucidated its electrical properties by patterning it and connecting it to electrodes. “They were not the first ones ever to see graphene, but certainly it was Geim and Novoselov who really opened the door to be able to study it,” says James Tour, professor of chemistry at Rice University.
Once they developed this experimental system for studying the material, Geim and Novoselov, and other researchers who followed, found some remarkable things. First, electrons in graphene behave as if they have no mass, careening forward at speeds of one million meters per second. (Compare that to the speed of light in a vacuum, 300 million meters per second.) And while electrons usually bounce off obstacles inside a conductive material, electrons traveling through the perfect honeycomb lattice of graphene have smooth sailing.
Graphene’s perfect structure gives rise to exotic quantum effects that are being studied by physicists. However, the material’s electrical properties, its transparency, and its strength have been seized on by engineers working to make everything from touch screens to solar cells to lightweight structural materials. Researchers at IBM are developing arrays of graphene transistors that leave conventional silicon in the dust, and a group at Samsung is developing printed graphene electrodes for use in transparent, flexible touch screens.
In recognition of the promise of the material, TR featured work at Georgia Tech on graphene transistors as one of the most promising emerging technologies in 2008; in the same year we recognized Novoselov with our young innovator award, the TR35.
Geim and Novoselov’s technique can be used to make graphene in relatively small quantities, enough to study it in the lab and make test devices, but nowhere near enough for manufacturing. In the intervening years, researchers have developed methods for making larger quantities of the material, and now they’re learning how to use it to make devices.
“Now we have to find ways of synthesizing graphene reliably on a large scale, and making these technologies reproducibly in a way that makes economic sense,” says Phaedon Avouris, a researcher developing graphene transistors and photodetectors at IBM’s Watson Research Center in Yorktown Heights, New York.