To Shrink electronics circuits further, in sizes of atomic
thickness, opto lithography and the present semiconductor
material such as silicon is not serving the purpose.
The paradigm shift in this direction is nanotechnology
by using the carbon material graphene. Graphene can be built
in atomic thickness (an atom or two atom thick graphene
sheets can be prepared) but the challenge here is to make
graphene work like electronic devices such as diode, transistor,
MOSFET, and also wiring them as electronic circuits. There
is some progress made recently in graphene based electronic
devices & circuits.
To make devices out of graphene, the graphene material
is deposited over another thin material, which can be insulator
or even a semiconductor material such as SiC (Silicon Carbide).
To form transistors scientists are trying out self-assembling-transistors
made up of nanowires.
In the present Silicon MOSFETs, the gate is etched between
drain and source. In case of graphene based transistors
a solution of nanowires are poured over graphene & they
are aligned to form transistor electronics by using different
process than the present VLSI chip making technology.
But placing billions of nanowires over a space or few square
centimeters is turning out to be very challenging, mainly
ensuring reliability of the device. Another challenge is
creating a graphene layer by using a process, which is suitable
for volume manufacturing
Some of the recent achievements in building nanotech based
electronics circuits based on graphene includes:
The researchers at UCLA were able to deposit nanowire on
an atom scale graphene. The transistors built using graphene
out perform silicon in frequency performance.
These graphene based transistor have the ability to operate
in tera Hertz - frequency ranges.
The team at UCLA used dielectrophoresis assembly approach
to precisely place nano-wire gate array on large area graphene
layer created by chemical vapor deposition (CVD). The deposition
has made on a glass substrate instead of semiconductor substrate.
This helped the devices to operate at frequencies of 10GHz.
Due to the well-accepted thermal and & electron mobility
properties of graphene, graphene is scientists favorite
material.
The paper titled "high speed graphene transistor with
a self aligned nanowire gate" by these researchers
at UCLA is available on nature magazine.
To nature magazine link on this subject is
http://www.nature.com/nature/journal/v467/n7313/full/nature09405.html
Another set of researchers at IBM were able to build wafer-scale
graphene IC smaller than pin head. The new IC consisting
of graphene transistors and a pair of inductors are completely
integrated on a silicon carbide (sic) wafer. IBM researchers
claim they achieved this despite the poor adhesive quality
of graphene with metals. To know more on this visit
http://www-03.ibm.com/press/us/en/pressrelease/34726.wss
Material scientists at Rice University find a new way to
control electronic properties of graphene alloy. Rice researchers
were able to create intricate patterns of graphene that
are separated by a similarly thin non conduct material made
up of nitrogen and boron.
The carbon graphene is called black graphene & the
graphene made of nitrogen & boron is called white graphene.
Scientist Boris Yakobson and colleagues describe a discovery
that could make it possible for nanoelectronic designers
to use well-understood chemical procedures to precisely
control the electronic properties of "alloys"
that contain both white and black graphene.
The researcher claim they can precisely predict the electronic
properties of the final product based solely upon the conditions
- technically speaking, the so called 'chemical potential'
during synthesis.
Rice release on this is available at
http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=16018&SnID=738520921
And find more at
http://pubs.acs.org/doi/full/10.1021/nl2011142
Here are links to useful articles, white papers and publications
related to graphene based transistors and devices
To learn on the low-noise top-gate graphene transistors
visit the link
http://arxiv.org/pdf/0908.3304
There are set free papers and research finding available
at the link on the subjects
bilayer graphene channel transistor
epitaxial graphene on SiC
Computational study of tunneling transistor based on graphene
nanoribbon
dual-gated graphene field-effect transistor
Graphene-based spin-pumping transistor
op-gated bilayer graphene transistor
Triple-mode single-transistor graphene amplifier and its
applications
Logic gates with a single graphene transistor
photocurrent imaging and efficient photon detection in a
graphene transistor
bilayer graphene channel transistor
Triple-mode single-transistor graphene amplifier and its
applications
op-gated bilayer graphene transistor
dual-gated graphene field-effect transistor
All the above can be find in the below link:
http://www.ieeepaper.com/free-ieee-paper-graphene- transistor.htm
Another paper on application of Graphene to High-Speed
Transistors:
Expectations and Challenges; Discovery of Graphene; Potentiality
of Breaking
through the Limitations of Semiconductors is available at
http://www.nistep.go.jp/achiev/ftx/eng/stfc/stt037e/qr37pdf/STTqr3705.pdf
The paper titled "Hysteresis of Electronic Transport
in Graphene Transistors" is available at
http://arxiv.org/pdf/1011.0579
"High-Performance Flexible Graphene Field Effect Transistors
with Ion Gel Gate Dielectrics" written by researchers
at Soongsil University, Seoul is available at:
http://chem.skku.edu/graphene/pdf/Beomjoon1.pdf
Reseachers at Pusan National University (PNU), Korea are
using carbon nanotubes and Graphene for renewable energy
devices.
Professor Kwang-Ho Kim and Assistant Professor Hyung Woo
Lee from the National Core Research Center (NCRC) at PNU
are working on a government-supported project for hybrid
materials based upon carbon nanotubes (CNT) and Graphene.
Their research is focussed on developing novel hybrid structures
containing CNT and Graphene which utilize the unique physical
and electronic properties of these materials to apply these
in various electronic devices such as solar cells and sensors.
