Physicists Advance Graphene Nanoelectronics
By Randolph Fillmore
TAMPA, Fla. (April 8, 2010) - In the expanding world of nanotechnology, where everything is measured in a billionth of a meter, new electronic nano-devices for future computer chips are under rapid development. However, controlling electronic activity in nano-devices has been a major challenge.
University of South Florida physicists have now discovered a new and better way to control the electrical properties of graphene - a single atom-layer of carbon that is the current material of choice for building future nano-electronics because of its exceptional electronic properties. While graphene is expected to push processing performance to speeds up to 100 times that of silicon-based electronics, the USF discovery will significantly advance graphene electronics.
The advancement in graphene electronics comes with their development of a process for making a one-dimensional extended defect in a sheet of graphene that can serve as a tiny nanowire several atoms across. Because this defect has metallic properties, it conducts electricity well. Subsequently, the new graphene nanowire can be used as an interconnect or as a structural element in electronic devices.
Their work is reported in the current issue of Nature Nanotechnology and also available online at http://www.nature.com/nnano/journal/vaop/ncurrent/abs/nnano.2010.53.html
“Silicon is up against a brick wall,” says Matthias Batzill, PhD, an assistant professor in the USF Department of Physics. “Because current silicon-based devices will not function below the ten nanometer level, there is an urgent need for a new material that can be used in smaller, yet faster, electronic devices.”
Graphene, derivied from graphite, a natural crystal phase of carbon, appears to be the material that promises to replace silicon and make electronic devices smaller and faster, but only if the controllability issue can be dealt with. The discovery of nanowire embedded in graphene made by USF team is a breakthrough in that effort.
“The well-defined atomic structure of the nanowire embedded in an atomically perfect graphene sheet can help address one of the biggest challenges of nanoelectronics – that is the formation of well-controlled contacts at the atomic level,” said Ivan Oleynik, PhD, associate professor in the USF Department of Physics.
According to Batzill, it is the development of the scientific principles for controlled tuning of graphene’s electronic properties by rearranging atoms at the nanoscale is what makes their work significant.
Supported by the National Science Foundation, their work contributing to the NSF initiative called Science and Engineering Beyond Moore’s Law. Postulated in 1965, Moore’s Law states that computer processing power based on silicon technology doubles every 18 months. However, as silicon devices get smaller and smaller, they may start to become dysfunctional at the ten nanometer size. Experts suspect that at this size limit, silicon circuits will start to leak electricity. Graphene may offer the solution to this problem, provided its conductivity can be altered in both a stable and controllable way.
“One way to tune the conductivity of graphene is by creating defects that are atomically stable,” said Batzill.
Instead of cutting the sheet of graphene to make the defect, the USF research team put two sheets of graphene side by side, but not perfectly aligned, leaving a zigzag, atomically precise “defect” between them. The defect constitutes an atomic wire.
“The success of our process leaves us with two different functional possibilities for this new one-dimensional defect,” concluded Oleynik. “We can use the defect as an interconnect, or a wire, for conducting electricity, or create something that can be used in building novel device architecture.”
The research team also included graduate student Jayeeta Lahiri, undergraduate student Pinar Bozkurt and postdoctoral associate You Lin.
The University of South Florida is one of the nation's top 63 public research universities and one of only 25 public research universities nationwide with very high research activity that is designated as community engaged by the Carnegie Foundation for the Advancement of Teaching. USF was awarded $380.4 million in research contracts and grants in FY 2008/2009. The university offers 232 degree programs at the undergraduate, graduate, specialist and doctoral levels, including the doctor of medicine. The USF System has a $1.8 billion annual budget, an annual economic impact of $3.2 billion, and serves more than 47,000 students on institutions/campuses in Tampa, St. Petersburg, Sarasota-Manatee and Lakeland. USF is a member of the Big East Athletic Conference.