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Monday, May 20, 2013

Graphene is making physics richer !

Graphene crystallographically aligned on boron nitride flakes is found to exhibit second generation Dirac points and reversal of Hall effect. Cloning of Dirac points is observed under high magnetic field leading to third generation Dirac points. The results pave way for controlling the electronic structure of graphene in superlattice configurations.

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12187.html

Thursday, May 16, 2013

Photoresponsive graphene

It is known that graphene has no band gap and hence does not exhibit photoreponse. However, by band structure engineering, one can open up the band gap. In a recent report, researchers have obtained a high photoresponsivity of around 8 A/W in monolayer graphene by creating electron trapping centres. The results pave way for optoelectronic applications of graphene.

http://www.nature.com/ncomms/journal/v4/n5/abs/ncomms2830.html

Wednesday, May 1, 2013

Mie scattering analog in graphene

It is proved theoretically that Dirac electron wave in graphene can be manipulated similar to Mie scattering of light on small particles. It is realized by using circular gating region in graphene which acts as a quantum dot.

http://prb.aps.org/abstract/PRB/v87/i15/e155409

Negative differential conductance in graphene transistors

Graphene's low density of states have been utilised for resonant tunneling through a boron nitride film and negative differential conductance in graphene transistors. The device is comprised of a few layer thick boron nitride layer sandwiched between graphene layers. The few atomic thick device promises to have ultrafast transient times.

http://www.nature.com/ncomms/journal/v4/n4/abs/ncomms2817.html?WT.ec_id=NCOMMS-20130430

Thursday, April 18, 2013

Graphene nanostructures- a promised plasmonic platform for mid-infrared region

The investigation of the pathways by which plasmon, a quanta of collective oscillations of electrons, loses energy is very important for plasmonic science and technology. Graphene plasmonic structures in this direction are very helpful. Researchers have used CVD graphene nanostructures to understand the damping of plasmons in graphene and observed that substrate plays a vital role in significant plasmon dispersion and damping.

http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2013.57.html

Tuesday, April 16, 2013

Loudspeakers made out of graphene


Chemical vapor deposited graphene has been used to make an audio device where graphene coated PVDF film can emit sound waves in a range of frequencies with high sound pressure level and low harmonic distortion. This demonstrates that graphene has uses which one has to think. The results are published in Applied Physics Letters:

http://apl.aip.org/resource/1/applab/v102/i15/p151902_s1

Tuesday, April 2, 2013

A graphene based hot electron transistor

In a recent study published in Nano Letters, experimentalists have demonstrated DC functionality of graphene based hot electron transistor. Moreover, the device is integrated using fabrication steps which are compatible with Si technology. An on/off ratio exceeding 10E4 is reported for graphene based transistor.
The findings open doors for graphene device market.