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Micromechanical Exfoliation and Graphene: 1999 papers and brief discussion of them
The discovery of a new material type, graphene and extremely thin platelets of graphite, was discussed in several articles from my research group published in 1999:
Lu XK, Huang H, Nemchuk N, and Ruoff RS, Patterning of highly oriented pyrolytic graphite by oxygen plasma etching, APPLIED PHYSICS LETTERS, 75, 193-195 (1999).
Lu XK, Yu MF, Huang H, and Ruoff RS, Tailoring graphite with the goal of achieving single sheets, NANOTECHNOLOGY, 10, 269-272 (1999).
These are downloadable on http://bucky-central.mech.northwestern.edu/publications.html
As #81 and #82.
The Conclusion of the article in NANOTECHNOLOGY states:
"4. Conclusions
The results of the study show that graphite islands of
micrometre size can be fabricated on the HOPG surface in
a designed way. The islands can be further manipulated by
an AFM tip either in situ as-created on the HOPG surface,
or as-transferred on any other flat surfaces, such as a Si(001)
surface. Very thin sections of HOPG plates were found on
the substrate to which the islands were transferred. The
results have the implication that, by using nanofabrication
techniques, single or multiple atomic layers of graphite sheets
can be fabricated in any desired shape. These graphite
sheets are suitable to be used as building elements for
new nanostructral materials and nanodevices. Micrometreor
nanometre-sized graphene sheets can, in principle, be
obtained from the graphite islands created from HOPG,
within the size range of current nanofabrication techniques.
Futurework will include trying to obtain graphene rather than
multiple-layer thick pieces of graphite, and to understand the
physical and chemical properties of graphene and few-layer
thick pieces of graphite."
Philip Kim's group at Columbia University then used a tipless AFM Cantilever to cleave such pillars of graphite, citing our work. I thought this a rather clever approach. While it is seen from the above statement and these two articles that significant work related to preparing graphene had been published in 1999, perhaps not all researchers are aware of this early work, given the recent flurry of activity using related methods of microexfoliation, such as peeling with an adhesive tape followed by rubbing on a Silicon wafer. The purpose of this posting is to bring this work to the attention of the mechanics community and to point out that advances in micro-exfoliation (removing the human hands from the effort?) might be useful research directions for preparing more controllably, thin platelets of graphite.
-Rod Ruoff
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Comments
applications of graphene sheet
In this year, there was a report by Craighead and McEuen's group on the electromechanical resonator from graphene sheet (for details, see their publication at Science Vol. 315, p490). The graphene sheet might be useful for further development of NEMS device for various applications (e.g. biosensor).
Graphene, 1-atom-thick sheet of carbon, 1st made 2004 or 1999?
It was reported in the Physics World 2006 that: Graphene is a one-atom-thick sheet of carbon that was isolated for the first time in 2004 – a feat long thought to be impossible.
Seems that you have already reported the fabrication in 1999. Why there is such difference?
good question
Hi Henry,
A good question. In our work, we invented a method of patterning graphite and of creating very thin platelets by applying shear by simply rubbing a Si wafer over the pillars that had been created by the patterning. It is possible that some of the thin platelets created by that step were individual layers, but our method of investigating the platelets, scanning electron microscopy, did not allow that to be proved or disproved.
So, it is fair to say that our work has strongly influenced the micromechanical exfoliation methods in use by physicists that have led to discoveries of fascinating transport properties in individual layers, and that we clearly outlined that this sort of approach might lead to interesting directions for nanoelectronics and other devices. I hope you enjoy reading our articles from 1999.
-Rod Ruoff