Hongjie Dai talks with
ScienceWatch.com and answers a few questions about
this month's Fast Breaking Paper in the field of
Chemistry.
Article Title: Chemically derived, ultrasmooth
graphene nanoribbon semiconductors
Authors: Li, XL;Wang, XR;Zhang, L;Lee,
SW;Dai,
HJ
Journal: SCIENCE
Volume: 319
Issue: 5867
Page: 1229-1232
Year: FEB 29 2008
* Stanford Univ, Dept Chem, Stanford, CA 94305 USA.
* Stanford Univ, Dept Chem, Stanford, CA 94305 USA.
* Stanford Univ, Adv Mat Lab, Stanford, CA 94305 USA.
Why do you think your paper is highly
cited?
This is the first time that graphene nanoribbons with true nanometer width
and very smooth edges were made. And it is the first experimental
demonstration showing that all the sub-10nm ribbons are semiconducting at
room temperature. This proves the theory that all graphene nanoribbons with
very narrow width are semiconducting, and puts graphene nanoribbons at the
forefront of making real field-effect transistors for computer chips or
other electronic devices.
Because the graphene nanoribbon is a new type of electronic material and
also a promising candidate to replace silicon in future electronics, it
also offers a number of things for scientists to play with. I think this
paper is of primary interest to chemists, material scientists, experimental
and theoretical physicists, and also to electrical engineers. This is
probably why it is being highly cited.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
This paper describes a new discovery. We developed a chemically derived
method to make graphene nanoribbons with a very smooth edge and a width
ranging from about 50nm to sub-10nm. We found that all these sub-10nm
graphene ribbons are semiconductors and gave a high on/off ratio
field-effect transistor at room temperature, which proved previous
theoretical predictions.
Would you summarize the significance of your paper in
layman's terms?
We developed a chemical method to make a new type of material with
high-quality, well-defined structure, and very narrow width (10-9nm). This
kind of material might be used to make future electronic devices when
silicon has met its limits.
How did you become involved in this research, and were
there any problems along the way?
Our group has always worked to achieve pure semiconducting carbon nanotubes
and assemble/align them into field-effect transistor arrays for future
nano-electronics. We have already made great progress.
Graphene nanoribbons could be looked at as unzipped single-wall carbon
nanotubes, only all are semiconducting when they have a very narrow width.
This enabled graphene nanoribbons to be another kind of promising material
for use in future nanoelectronics. Thus, we began to work in the field of
graphene nanoribbons, where it is quite difficult to separate graphene
sheets into a freestanding form from bulk graphite. As the yield of a
graphene nanoribbon is not very high, we spent quite a bit of time in
trying to improve the ribbon yield.
Where do you see your research leading in the
future?
We developed a chemical method to make graphene nanoribbons that could be
transformed into good field-effect transistors. We are trying to improve
the graphene nanoribbon yield and the ribbon quality, which then might lead
to a bottom-up method of assembly for making logical circuits.
Our research has helped lead many other scientists toward the development
of newer methods for making sub-10nm graphene nanoribbons and also in the
investigation of their physical properties. We believe we will continue to
be a leader in the area of making logical circuits, and even computer
chips, using these sub-10nm graphene nanoribbons.
Do you foresee any social or political implications for
your research?
Our graphene nanoribbons could possibly be used in future graphene-based
electronics such as computer chips or gas sensors.
Hongjie Dai
J.G. Jackson-C.J. Wood Professor of Chemistry
Department of Chemistry
Stanford University
Stanford, CA, USA