According to an article at the PhysOrg.com site, IBM scientists have just announced, in a paper [abstract] published in Science, that they have created a new type of high-speed transistor using graphene (a particular form of carbon) that has the potential to replace silicon devices in high-speed applications. From the abstract:
The high carrier mobility of graphene has been exploited in field-effect transistors that operate at high frequencies. Transistors were fabricated on epitaxial graphene synthesized on the silicon face of a silicon carbide wafer, achieving a cutoff frequency of 100 gigahertz for a gate length of 240 nanometers.
Graphene is a form of solid carbon in which the carbon atoms are arranged in a “honeycomb” hexagonal lattice, spaced about 0.142 nanometers apart. It has sometimes been described as looking like “atomic-scale chicken wire”, which is not entirely fanciful when one looks at the image below, from a transmission electron microscope.
Image from:Albert Dato, Zonghoon Lee, Ki-Joon Jeon, Rolf
Erni,Velimir Radmilovic,Thomas J. Richardson,and Michael
Frenklach,Chem. Commun., 2009, 6095 - 6097
The structure of graphene (which is similar to the structure in a benzene ring) means that electrons can move through the material very rapidly. The high frequency (100 GHz) achieved by the IBM researchers was using a device fabricated with techniques compatible with semiconductor manufacturing.
“A key advantage of graphene lies in the very high speeds in which electrons propagate, which is essential for achieving high-speed, high-performance next generation transistors,” said Dr. T.C. Chen, vice president, Science and Technology, IBM Research. “The breakthrough we are announcing demonstrates clearly that graphene can be utilized to produce high performance devices and integrated circuits.”
This is a noteworthy step, since state-of-the-art silicon devices of the same modest gate size (240 nanometers) have a cutoff frequency of about 26 GHz. High-frequency capability is inversely related to gate size, so there is a good chance that graphene devices with smaller gates will produce even faster performance.