Graphene make light work - a boon for optoelectronic applications of graphene

Graphene (Ms. G, as I call it QUEEN of 2D materials :-) ) , since 2004, has demonstrated her acrobatism with number of applications in various fields viz. transparent and flexible electronics, touch screens etc. Now, graphene has been demonstrated as a infrared photodetector which can convert light signals to electrical signals. This makes graphene the leading material so far which can be used for electrical as well as optical applications.

http://www.nature.com/news/graphene-makes-light-work-of-optical-signals-1.13744

Polycrsytalline graphene is as strong as single crystalline graphene!

Good news for mechanical applications of graphene - 

Researchers have measured the intrinsic strength of single crystal and bicrystal graphene grown using chemical vapor deposition. They have found that polycrystalline graphene with high angle grain boundaries are as strong as single crystal graphene. The high strength is attributed to the atomic-scale strain fields, determined by a transmission electron microscope, in the carbon-carbon bonds at the boundary. 

http://www.nature.com/ncomms/2013/131119/ncomms3811/full/ncomms3811.html?WT.ec_id=NCOMMS-20131120

Graphene nanoribbons (GNRs) grown using PMMA !

Graphene nanoribbons (GNRs) are very promising material for electronic applications as quantum confinement opens a band gap in gapless graphene. Now researchers have used PMMA, a polymer used as a support to transfer graphene, to grow GNRs on epitaxial Ni thin films. The study paves for controlling the orientation of GNRs. 

http://pubs.acs.org/doi/abs/10.1021/nn405122r

We all get confused by the name "graphene" as it has now become a routine to use the word for many 2D carbon materials which actually are not real "graphene". One can have a look at the following article which provides a recommended nomenclature for 2D carbon materials. Its a must read for newcomers and a guide for those who are already in the field.

http://www.sciencedirect.com/science/article/pii/S0008622313008002

"Graphene Handbook" is in the market now. I think its first of its kind. The chapters in the book spans from graphene fundamentals to its market commercialization. 
http://www.graphene-info.com/handbook/?goback=%2Egde_5153830_member_5808166566264598530#%21

Controlling number of Dirac points in graphene- Band structure engineering

Researchers from India have demonstrated control on the number of Dirac points in graphene by using a superlattice structure. The work is promising in controlling not only the electronic but magnetic and thermo-electric properties of graphene as well.

http://pubs.acs.org/doi/abs/10.1021/nl4006029

Dual gated bilayer graphene shows photothermal response

Graphene is seen as a potential candidate for photodetection applications. Now, the researchers have studied dual gated bilayer graphene to observe the gating effect on its photothermal response. They have found a significant role of hot electron thermal relaxation in defining the photovoltaic response of graphene.

http://prl.aps.org/abstract/PRL/v110/i24/e247402

Multilayer graphene shows temperature dependence of far-infrared response

Graphene possesses miracle optical properties with exhibition of broadband transmission irrespective of the wavelength of light. However, researchers have found a temperature dependence of far-infrared response of epitaxial multilayer graphene. The results are vital for graphene based devices.

http://apl.aip.org/resource/1/applab/v102/i23/p231906_s1

Flexible graphene radio frequency devices

The mechanical strength of graphene allows one to fabricate flexible devices. The researchers have now demonstrated flexible graphene radio frequency devices with cut off frequencies as high as 10 GHz with a temperature stability upto 400 K. 

http://apl.aip.org/resource/1/applab/v102/i23/p233102_s1

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

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

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

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

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

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.

http://pubs.acs.org/doi/abs/10.1021/nl304305x?mi=ya8wwg&af=R&pageSize=20&title=graphene

Hot carrier generation in graphene !

In a recent study, researchers have analyzed different pathways contributing to the ultrafast relaxation of photoexcited carriers in graphene using tetra-hertz pump spectroscopy. The results indicate that carrier-carrier scattering is the dominant mechanism leading to the generation of hot electrons in graphene. These hot carriers in turn can drive current in graphene enabling its high efficiency optoelectronic applications.

http://www.nature.com/nphys/journal/v9/n4/full/nphys2564.html?WT.ec_id=NPHYS-201304

Electron optics applications of graphene

Transverse magnetic focusing has been observed in graphene and is expected to open new application area of graphene in electron-optics. In a recent report published in Nature Physics, researchers have used ambipolar nature and ballistic transport properties of graphene to study the transverse magnetic focusing effect upto room temperature.

http://www.nature.com/nphys/journal/v9/n4/full/nphys2549.html?WT.ec_id=NPHYS-201304

Graphene used as a platform to observe atomic collapse

Researchers have imaged atomic collapse in Ca dimers placed on CVD graphene/BN stack using STM. This became possible because charge carriers in graphene behave as massless relativistic particles. 

http://www.sciencemag.org/content/early/2013/03/06/science.1234320.full

Graphene devices go for integration with Si- A new approach

The quest is on for integrating graphene with Si and is a dreamwork for nanoelectronics. In this direction, researchers have developed a new 'manufacturable process integration' (MPI) approach for fabricating graphene devices. The approach can be a significant milestone to enter in the era of nanoelectronics based on 2D materials.

http://www.sciencedirect.com/science/article/pii/S0038110113000658