IBM researchers have demonstrated the operation of graphene field-effect transistors at GHz frequencies, claiming the highest frequencies reported so far using the non-silicon electronic material.

IBM is a long-time proponent of graphene - a special form of graphite, consisting of a single layer of carbon atoms packed in "honeycomb lattice" - as a material for building nanoelectonic circuits smaller than those in today's silicon-based computer chips.

The company in March announced that it discovered a way to suppress unwanted interference of electrical signals that are created when shrinking graphene. That development was followed closely by research from the University of Maryland that found that electrons travel more than 100 times faster in graphene than in silicon.

Specifically, IBM said today that its scientists have fabricated nanoscale graphene field-effect transistors and demonstrated the operation of graphene transistors at the GHz frequency range, establishing scaling behaviour for the first time.

With a top-gate design and a gate length 150nm, IBM's team achieved a cut-off frequency of 26 GHz for graphene transistors, the company said.

IBM researchers expect that by improving the gate dielectric materials, the performance of these graphene transistors could be further enhanced. They expect that THz graphene transistors could be achieved in an optimised graphene transistor with a gate length of 50nm. IBM said its researchers also plan to pursue RF circuits based on these high-performance transistors.

IBM described it as an important milestone for the Carbon Electronics for RF Applications (CERA) program sponsored by DARPA, as part of the effort to develop the next-generation of communication devices.

The graphene field-effect transistor work is performed by inter-disciplinary collaboration at IBM TJ Watson Research centre.

By Suzanne Deffree, Managing Editor, News - Electronic News

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