Yu-Ming Lin talks with
ScienceWatch.com and answers a few questions about
this month's New Hot Paper in the field of Chemistry. The
author has also sent along images of his work.
Article Title: Operation of Graphene Transistors at
Gigahertz Frequencies
Authors: Lin, YM;Jenkins, KA;Valdes-Garcia,
A;Small, JP;Farmer, DB;Avouris, P
Journal: NANO LETT
Volume: 9
Issue: 1
Page: 422-426
Year: JAN 2009
* IBM Corp, Thomas J Watson Res Ctr, Yorktown Hts, NY 10598
USA.
* IBM Corp, Thomas J Watson Res Ctr, Yorktown Hts, NY 10598
USA.
(addresses have been truncated.)
Why do you think your paper is highly
cited?
Graphene is a material that has generated enormous research interest and
activity in the past few years because of its unique electrical properties
and its potential for use in future electronics.
This paper is likely well-cited because it presents one of the first
experimental demonstrations of gigahertz graphene transistors with the
highest frequency reported thus far, and establishes the scaling behavior
of device performance with respect to the device dimension. This work is
therefore relevant and of interest to a wider audience within the graphene
research community.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
In this paper, we presented an approach to fabricate top-gated graphene
transistors using exfoliated graphene extracted from a graphite crystal,
and demonstrated the operation of the graphene transistors at a frequency
as high as 26 gigahertz, or 26 billion cycles per second.
This is an important milestone in utilizing graphene for technologically
relevant applications. We also investigated, for the first time, the
scaling behavior of graphene devices as the device dimension shrinks, which
exhibits a different trend from that of conventional semiconductors.
Top-gated graphene field-effect transistor. Inset: Scanning
electron microscope image of a graphene device.
In our latest work,"100-GHz Transistors from Wafer-Scale Epitaxial
Graphene," Y.-M. Lin, et al., published in Science
327(5966): 662, 2010, we further demonstrated a large-scale epitaxial
graphene synthesis on a SiC wafer and achieved graphene transistor
operational frequencies of up to 100 gigahertz.
Would you summarize the significance of your paper
in layman's terms?
Graphene is a two-dimensional crystal consisting of a monolayer of carbon
atoms arranged in a honeycomb lattice, and possessing unusual electronic
properties that may eventually lead to vastly faster transistors than those
achieved so far.
By placing a metal gate electrode on the graphene channel, we demonstrated
a graphene transistor that is capable of amplifying electrical signals at
very high frequencies. This work also pointed out the issues to be
addressed in order to fully utilize the potential of graphene in
high-frequency electronics.
How did you become involved in this research, and
were there any problems along theway?
This study was funded by the Defense Advanced Research Projects Agency
(DARPA), the research arm of the US Department of Defense, to explore
Carbon-based Electronics for Radio-frequency Applications (CERA).
I was already exploring electrical transport properties of graphene and its
nano-ribbons, and became involved with the fabrication and characterization
of graphene transistors when the CERA program was launched in May, 2008.
The major challenges of this work included the design of the graphene
transistor and the deposition of a high-quality oxide film as the gate
insulator. My colleagues Dr. Keith Jenkins and Dr. Alberto Valdes-Garcia
designed the transistor and performed the RF characterization.
Another great challenge involved the deposition of a high-quality insulator
on graphene without deteriorating its transport properties, and this issue
was successfully addressed by a process developed by Dr. Damon Farmer. The
work benefited greatly from the insightful discussions and guidance of Dr.
Phaedon Avouris.
Where do you see your research leading in the
future?
Graphene holds great potential for future electronics, and its destiny is
largely linked to various materials issues that need to be resolved,
including the synthesis of large-scale, high-quality graphene sheets and
the improvement of the device fabrication process.
I hope the impact of this research could lead to graphene-based integrated
circuits for analog and, perhaps, digital applications.
Do you foresee any social or political
implications for your research?
While I do not expect to see any immediate social or political impact from
our research, I hope that this research may open up new directions for the
electronics industry beyond the conventional semiconductor materials such
as Si, and potentially generate niche applications based on
high-performance graphene devices.
Yu-Ming Lin
Research Staff Member
Nanoscale Science and Technology Group
IBM T. J. Watson Research Center
Yorktown Heights, NY. USA Web