Electronics - Page 37

Trying to investigate several doping methods for graphene, researchers have found a way to dope graphene with light. This kind of doping is selective and reversibly - meaning that you can change the material attributes using different light colors, angles or polarization. To achieve that doping method, the researchers attached a plasmonic nano antenna to the graphene. The graphene was doped by hot electrons generated from the antenna.

The doping can be controlled by changing the antenna size or the laser's wavelength and power density. n-type graphene provided a larger doping efficiency than p-type graphene.

Researchers from the US Naval Research Laboratory (NRL) discovered a way to use graphene as an extremely thin "tunnel barrier" to conduction. This could be very useful for Spintronics devices. The researchers have shown that graphene can serve as an excellent tunnel barrier when current is directed perpendicular to the plane of carbon atoms. The spin polarization of the current is also preserved by the tunnel barrier.

The researchers replaced the normally used oxide barriers (which introduce defects into the system and feature too high a resistance) with graphene - which is defect resistant and chemically inert and stable.

Researchers from the Rice University have developed highly transparent (95%), flexible, nonvolatile resistive memory devices based on silicon oxide (SiOx) and graphene. This research began in 2008 when they discovered that silicon oxide itself can be a switch. The researchers placed the SiOx and crossbar graphene terminals on flexible plastic.

The new design is much simpler than current flash memory devices as it uses only two terminals and can be stacked in 3D configurations. This can vastly increase the density of memory devices. This memory can also be made in a multi-state mode (i.e. not just binary 1/0).

Researchers from the Norwegian University of Science and Technology (NTNU) developed a new way to grow gallium arsenide (GaAs) nanowires on graphene using molecular beam epitaxy. The new hybrid electrode material offers excellent optoelectronic properties.

The researchers have patented the new technology and established a new company to commercialize it called CrayoNano AS. According to the company the new technology can be easily be used with existing production equipment.

Researchers from Cornell University have managed to pattern single atom films of graphene and boron nitride, an insulator, without the use of a silicon substrate. They are using a technique they call patterned regrowth, and they say this could lead towards substrate-free, atomically thin circuits. These will be so thin that they could be transparent and flexible, and yet have great electrical performance.

Patterned regrowth uses the same basic photolithography technology used in silicon wafer processing, and it allows graphene and boron nitride to grow in perfectly flat, structurally smooth films. The researchers first grew graphene on copper and used photolithography to expose graphene on selected areas, depending on the desired pattern. They filled that exposed copper surface with boron nitride, the insulator, which grows on copper and fills the gaps. Then you simply peel off the entire structure.

Researchers from IBM and University of California Riverside managed to make the slimmest graphene nanoribbon (GNR) ever - just 10 nm in width. Making one is virtually impossible, and the team created a large number of GNRs in parallel. The researchers say that the arrays cover about 50% of the prototype device channel area, which means that integrated circuits based on GNRs with the required high current densities are now possible. The narrow GNRs have a bandgap of about 0.2 eV.

The process the researchers used consists of two main steps: a top-down e-beam lithography step and a bottom-up self-assembly step involving a block copolymer template comprising alternating lamellae of the polymers PS and PMMA.

Researchers from Manchester University have used a new side-view imaging method to individually visualize graphene sheets in a layered insulated stack of sheets. They found out that each graphene layer in such a structure is perfectly aligned, even with 10 layers. This was a surprise as they expected the graphene to be distorted.

This means that stacking graphene sheets does not degrade their properties. This means that you can stack graphene to create 3D chips - which will have a massive improvement in processing speed or storage capacity compared to a 2D chip.

Researchers from Samsung's Advanced Institute of Technology have developed a new graphene-silicon Schottky barrier that enables graphene to switch electric current on and off. The researchers explored potential logic device applications based on this technology.

Researchers from the University of Wisconsin-Milwaukee developed a new material called Graphene Monoxide (GMO) which is semiconducting. It's also may be easier to scale up compared to Graphene. This new material can provide the key towards graphene based electronics. The researchers say that they discovered GMO by chance...

In their experiments, the team heated Graphene Oxide in a vacuum, to reduce oxygen. But the results surprised them - the the carbon and oxygen atoms in the layers of GO became aligned, transforming themselves into an ordered semiconductor - the GMO.

Researchers developed a new process to make flexible transistors from graphene. The new process enable high electron mobility and high frequencies (in the Ghz range). The process uses a graphene in a solution and places it on polyimide substrates.

The idea is to deposit sheets of graphene in solution on the polyimide with an alternating electric field applied between electrodes made in advance. This technique, known as dielectrophoresis or DEP, is used to guide the graphene deposition process so as to obtain a high density of deposited sheets in certain spots. This density is essential for achieving outstanding high-frequency performance.