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Nanotechnology

Graphene Circuits: Making electronic circuits using carbon material graphite

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.



electronic components

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

electronic components

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.


 

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