Photonics - Page 9

The UK's Engineering and Physical Sciences Research Council (EPSRC) awarded the University of Nottingham with £1.3 million (just over $2 million) that will be used to buy a new molecular beam epitaxy (MBE) system. This new system will enable the growth of high quality, large area layers of graphene and boron nitride.

Researchers from the University plan to study new materials based on graphene and boron nitride for electronic and optoelectronic applications.

Researchers from University of Exeter have developed a new flexible, transparent and ultra-lightweight photodetector device made from graphene and graphExeter (a room-temperature transparent conductor discovered at the University of Exeter in 2012). The new device can also be used to generate electricity. It's only a few atoms thick and can be woven into textiles to create photovoltaic fabrics.

The researchers say that the efficiency of the new device is similar to opaque devices based on graphene and metals (Nokia, for example, is working on graphene-based photo detectors). The new device does not contain any metals. It can detect light across the entire visible light spectrum.

Researchers from IBM are studying how plasmons lose their energy in graphene. It turns out that plasmons lose their energy very slowly in graphene, which is good for photonics and quantum optics applications (the longer the plasmons last, the better).

The IBM researchers are using graphene nanoribbons, dots and nanodisk arrays grown on all sorts of substrates (silicon wafers, diamond-like carbon and SiO2, to name just a few). The researchers are using a new technique (based on Fourier transform IR spectrometer) to measure exact plasmon damping mechanisms and rates. Their most important finding is that the graphene plasmons appear to interact strongly with the vibrations of the silicon dioxide substrate surface atoms on which the graphene is deposited. This leads to so-called energy-dependent hybrid plasmon-phonon modes that disperse and decay very differently compared with those modes where graphene is deposited on non-planar diamond-like substrates.

Researchers from the Oak Ridge National Laboratory (ORNL) documented silicon atoms "dancing" on a graphene sheet using scanning transmission electron microscope. The researchers trapped the silicon atoms (clusters of six atoms) on a graphene sheet using pores in the sheet.

The researchers say that this is the first time silicon atoms were directly seen that way. Using a simple electron beam is not useful because energy is inserted into the cluster. The ability to analyze small clusters is important as this can help understand how different atomic configurations control a material's properties. It could also be used to practical applications in areas such as electronic and optoelectronic devices, as well as catalysis.

Researchers from Harvard University developed a graphene-based electrically-tunable plasmonic mid-infrared antenna array. They say this device can be useful for multi-analyte sensors, reconfigurable meta-surfaces and optoelectronics devices.

This is the first time nanoantennas can be tuned to the mid-infrared part of the electromagnetic spectrum by simply applying a voltage. This works because a graphene sheet, placed in the nanogap of a dipole antenna, acts as an electrically tunable nano-circuit element.

Researchers from the ICFO, MIT, Max Planck and Graphenea have demonstrated that graphene is able to concert a single photon into several electrons (most materials generate a single electron in such a case). This means that Graphene is highly efficient in converting light to energy and can be an alternative material for light detection and energy harvesting.

The researchers used a single sheet of graphene and sent a known number of photos with different colors (energies). High energy photos (violet colored for examples) create more electrons than low energy photos (such as infrared colored ones).

Researchers from the University of Manchester and Aix-Marseille University developed a new optical device that can analyze a single molecule quickly, using Plasmonics (the study of vibrations of electrons in different materials). This could lead to virus detectors, fast and accurate athlete drug testing and explosive tracking in airports.

The device uses artificial materials with topological darkness that are highly sensitive to a single small molecule (this relies on topological properties of light phase). The artificial material is covered with graphene (which they say is one of the best materials that can be used to measure the sensitivity of molecules). Basically the device is like a single-molecule microscope.

Unlike graphene, graphene-oxide (GO) has a bandgap, but has poor electronic properties (due to disorganized arrangement of atoms). Now researchers from the University of Wisconsin—Milwaukee have developed a method to make ordered GO. They hope that this method will enable "ideal bandgap" carbon based devices to be used as transistors, sensors and optoelectronic devices.

The researchers made a device made from layers of oxygen-poor graphene sandwiched between layers of GO, and then annealed (heated) it. The resulting device (shown on the right of the image above) has a more complex and ordered structure (you can see this as the extra rings in the image).

AZ Electronic Materials have entered into a licensing and sponsored research agreements with William Marsh Rice University in the field of graphene nanoribbons (GNRs) for application to electronic and advanced optical devices. AZ will gain exclusive world-wide rights to several patent families invented by Dr. James Tour and his working group at Rice, covering preparation methods and application of GNRs.

This technology could potentially enable low-cost functionalize GNR production from commercially available carbon sources such as CNTs. The method developed at Rice is reductively open CNTs to provide high quality, highly conductive GNRs. This method also provides an easy way to chemically functionalize them at their edges, which leads to greatly enhanced stability of coating formulations without deteriorating the performance. This allows the GNRs to be formulated in solvents common to electronic device manufacturing processes, which can be coated on substrates by industry-known methods. AZ also licensed Dr. Tour's high-yield approaches to graphene oxide.

Scientists from the University of Manchester, including Nobel prize-winner Professor Andre Geim constructed a multi-layer graphene structure made by placing individual sheets one on top of the other. This 'cake' like structure behaves like a nanoscale electric transformer - which could be used to make new electronic transistors and photonic detector devices.

In the new device, electrons moving in one metallic layer pull electrons in the second metallic layer by using their local electric fields. The layers are only separated by a tiny (few interatomic) distance - much shorter than anything done before. To achieve this structure they used just four atomic layers of boron nitride to serve as an electric insulator.