Graphite - not graphene - could replace silicon transistors; Single-atom-thick layers of carbon have been touted as an alternative to the silicon transistor, but now it looks as if their multi-layered cousin might be a better bet
Jason Palmer A REPLACEMENT for the silicon transistor - the heart of the modern computer - may be closer than expected, thanks to a material discovered in the 16th century. For the last 20 years, the number of transistors that can be fitted onto a computer chip has doubled about every two years. This trend can't continue indefinitely, however, as shrinking silicon transistors down eventually makes them less efficient. Recently a substance called graphene - hexagonal arrays of carbon atoms in sheets one atom thick - has been touted as . One hundred times thinner than the smallest silicon transistor possible, graphene conducts electricity much more efficiently. It also has exotic electronic properties which could be useful in quantum computing. But there's a problem: graphene sheets tend to curl up and react with substances around them, making them difficult to build into devices. Now Yakov Kopelevich and Pablo Esquinazi of the State University of Campinas in Brazil claim that graphite, the substance used in pencil leads, might be a more useful alternative to silicon (Advanced Materials , DOI: 10.1002/adma.200702051). "All the properties of graphene are present in grahite," says Kopelevich. He and Esquinazi point out that graphite, which is made of multiple stacks of graphene sheets, is easier and cheaper to produce and doesn't curl up, thanks to the stabilising effect of the adjacent layers. In the last few years the pair have shown that, as with graphene, graphite's conductivity can be altered using a magnetic field and that current can flow through it as though carried by massless "particles" called Dirac fermions. Both properties will be important in future quantum computers. "It's good that we don't have to think only one layer [of carbon atoms] will do everything," says Jorge Sofo, a graphene researcher at Pennsylvania State University. But according to Millie Dresselhaus, a nano-electronics expert at the Massachusetts Institute of Technology, how much of the magic of graphene is found in graphite remains to be seen. It is not clear if graphite's electronic properties can be tuned to suit a specific application, for example, something done easily in graphene. -- sanjay Home Phone 02228122688 To unsubscribe send a message to [EMAIL PROTECTED] with the subject unsubscribe. To change your subscription to digest mode or make any other changes, please visit the list home page at http://accessindia.org.in/mailman/listinfo/accessindia_accessindia.org.in