IBM Researchers today announced that they demonstrated the operation of graphene field-effect transistors at GHz frequencies, and achieved the highest frequencies reported so far using this non-silicon electronic material.
This accomplishment is 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
Graphene is a special form of graphite, consisting of a single layer
of carbon atoms packed in honeycomb lattice, similar to an atomic
scale chicken wire. Graphene has attracted worldwide attention and
activities because its unusual electronic properties may eventually
lead to faster transistors than any transistors achieved so far.
The work is performed by inter-disciplinary collaboration at IBM T.
J. Waston Research Center. "Integrating new materials along with the
miniaturization of transistors is the driving force in improving the
performance of next generation electronic chips," said IBM
researchers involved in this project.
The operation speed of a transistor is determined by the size of the
device and the speed at which electrons travel. The size dependence
was one of the driving forces to pursue ever-shrinking Si
transistors in semiconductor industries. A key advantage of graphene
lies in the very high electron speed with which electrons propagate
in it, essential for achieving high-speed, high-performance
Now, IBM scientists have fabricated nanoscale graphene field-effect
transistors and demonstrated the operation of graphene transistors
at the GHz frequency range. More importantly, the scaling behavior,
i.e. the size dependence of the performance of the graphene
transistors was established for the first time. The team found that
the operation frequency increases with diminishing device dimension
and achieved a cut-off frequency of 26 GHz for graphene transistors
with a gate length of 150 nm, the highest frequency obtained for
graphene so far.
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 optimized graphene transistor with a gate length of
50 nanometers. In the next phase, the IBM researchers also plan to
pursue RF circuits based on these high-performance transistors.
The report on this work, entitled "Operation of Graphene Transistors
at GHz Frequencies" is published today in the journal Nano Letters
and can be accessed at