Feb 5, 2010
Graphene transistor breaks new record
IBM researchers have made the fastest graphene transistor ever, with a cut-off frequency of 100 billion cycles/second (100 gigahertz). After further downscaling and optimization, the device could far outperform conventional devices made from silicon, says the team.
Graphene – the one-atom-thick sheet of carbon discovered in 2004 – is unusual since electrons can move through it at extremely high speeds. This is because they behave like relativistic particles with no rest mass. This, and other unusual physical and mechanical properties, means that the "wonder material" could replace silicon as the electronic material of choice and might be used to make faster transistors than any that exist today.
Phaedon Avouris' team at IBM's TJ Watson Research Center in New York began by making high-quality graphene wafers by thermally decomposing a silicon carbide (SiC) substrate. They then used these to make the radio-frequency transistor, which comprises a metal top gate and a novel gate insulator stack involving a polymer and a high dielectric constant oxide. The gate length is relatively big at 240 nm, but it could be scaled down in the future to further improve device performance.
The graphene transistor already has a higher cut-off frequency than the best silicon MOSFETs with the same gate length (these have a cut-off frequency of around 40 GHz). The new device breaks IBM's previous record of 26 GHz, reported on in January 2009.
"Our work is the first demonstration that high-performance graphene-based devices can be fabricated on a technologically relevant wafer scale," Avouris told nanotechweb.org.
The high-frequency transistor could find applications in communications (wireless and point-to-point) and imaging, including high-resolution radar, medical and security imaging.
The IBM researchers now plan to scale down their transistor, improve graphene purity and optimize device architecture. "Such transistors could then far outperform conventional devices," said Avouris.
The result was published in Science.
About the author
Belle Dumé is contributing editor at nanotechweb.org