Electronics - Page 17

A team at the Department of Energy’s Oak Ridge National Laboratory and North Carolina State University has found a way to grow narrow ribbons of graphene without the use of metal substrates.

Narrow graphene ribbons can perform as a semiconductor if the ribbons are made with a specific edge shape, but to grow graphene nanoribbons with controlled width and edge structure from polymer precursors, is not a simple task. Previous researchers had used a metal substrate to catalyse a chemical reaction, but the metal substrate suppresses useful edge states and shrinks the desired band gap. The team in this work managed to grow graphene nanoribbons without a metal substrate. Instead, they injected charge carriers that promote a chemical reaction that converts a polymer precursor into a graphene nanoribbon.

Researchers from the University of Exeter have developed an innovative new memory using a hybrid of graphene oxide and titanium oxide. These devices are reportedly low cost and environmentally friendly to produce, and are also suited for use in flexible electronic devices such as 'bendable' mobile phone, computer and television screens, and even 'intelligent' clothing. These devices may also have the potential to offer a cheaper and more adaptable alternative to 'flash memory', which is currently used in many common devices.

The team stated: "Using graphene oxide to produce memory devices has been reported before, but they were typically very large, slow, and aimed at the 'cheap and cheerful' end of the electronics goods market. Our hybrid graphene oxide-titanium oxide memory is, in contrast, just 50 nanometres long and 8 nanometres thick and can be written to and read from in less than five nanoseconds—with one nanometre being one billionth of a metre and one nanosecond a billionth of a second."

Scientists at MIT, along with researchers from IBM, the University of California at Los Angeles, and Kyungpook National University in South Korea, have found a way to produce graphene with fewer wrinkles, and to iron out the wrinkles that do appear. The team reports that the techniques successfully produce wafer-scale, "single-domain" graphene - single layers of graphene that are uniform in both atomic arrangement and electronic performance.

After fabricating and then flattening out the graphene, the researchers tested its electrical conductivity. They found each wafer exhibited uniform performance, meaning that electrons flowed freely across each wafer, at similar speeds, even across previously wrinkled regions.

Researchers at the Czech Republic created magnetized carbon by treating graphene layers with non-metallic elements, said to be the first non-metal magnet to maintain its magnetic properties at room temperature. The researchers say such magnetic graphene-based materials have potential applications in the fields of spintronics, biomedicine and electronics.

By treating graphene with other non-metallic elements such as fluorine, hydrogen, and oxygen, the scientists were able to create a new source of magnetic moments that communicate with each other even at room temperature. This discovery is seen as "a huge advancement in the capabilities of organic magnets".

Researchers from the University of Exeter have developed a method using graphene oxide flakes that could be used to create the next generation of computers. The Exeter team used microfluidics technology to develop a new method of engineering computer chips that’s easier and less expensive than the current methodology.

The microfluidics approach uses minute channels to control the flow and direction of tiny quantities of fluid. The tests performed at the University of Exeter involved flakes of graphene oxide, mixed into the fluid, which was then mixed together in the channels to create the chips. The researchers used an advanced light-based procedure to facilitate the creation of three-dimensional structures that comprise the resulting chip.

As electronics keep shrinking in size, several problems arise. One of these is that the copper wires that connect transistors to form complex circuits need to be very thin, but carry so much current that can cause them to break apart due to atoms being knocked out of place. One way of solving this, studied by a group led by Stanford University, is to wrap copper with graphene. The group found that this can alleviate this major problem called electromigration.

This was presented at a recent IEEE meeting that addressed the coming problems for copper interconnects and debated ways of getting around them. Growing graphene around copper wires can help prevent electromigration, and also seems to bring down the resistance of the copper wires. Generally speaking, the narrower the wire, the higher its resistance. Interconnects have had to shrink while increasing the current densities by 20 times, said Intel Fellow Ruth Brain at the meeting.

Researchers from King Abdullah University of Science and Technology (KAUST), in collaboration with the Georgia Institute of Technology, have recently demonstrated a simple, solution-based, method for surface doping of few-layer graphene (FLG) using novel dopants (metal-organic molecules) that show a minimal effect on the optical transmission as compared to other dopants like metal chlorides.

This work investigates the effect of dopant strength and dosage on the electronic and electrical transport properties of doped FLG. Moreover, It reveals fundamental differences between the doping results in single layer graphene and few-layer graphene. The study focused on few-layer CVD graphene, rather than single-layer CVD graphene, a somewhat less common area of research to date.

A team of researchers affiliated with UNIST has designed a technique that greatly enhances the performance of Schottky Diodes (metal-semiconductor junction) used in electronic devices. The research findings are especially interesting as they address the contact resistance problem of metal-semiconductors.

The researchers have created a new type of diode with a graphene insertion layer sandwiched between metal and semiconductor. They demonstrated that this graphene layer not only suppresses the material intermixing substantially, but also matches well with the theoretical prediction that "In the case of silicon semiconductors, the electrical properties of the junction surfaces hardly change regardless of the type of metal they use".

Researchers from Graphenea, Thales, CNRS, the University of Cambridge and GERAC have announced the development of a stable platform for manufacturing electronic devices made of graphene. Graphene field effect transistors (GFETs) made using this platform are shown to be stable against atmospheric influences and uniform in their properties across a batch of more than 500 devices.

The researchers reported on a statistical analysis and consistency of electrical performance of GFETs on a large scale. The devices were protected and passivated with two protective layers that ensured that the conductance minimum characteristic of electrical transport in graphene is visible most of the time and that it fluctuates very little from device to device. The intrinsic charge doping was below 5x1011 cm-2. In addition, this approach removed the hysteresis effect that usually degrades graphene device performance in air. Importantly, the devices were also stable in time, with unchanged performance over the course of one month.

Grafoid, a leading graphene R&D and investment company, announced its entry into the global industrial coatings market with the introduction of its patent pending GrafeneX graphene coatings technology. Grafoid describes the GrafeneX technologies as a cost-effective way of laying down graphene coatings on large surface areas.

GrafeneX is a novel technology that creates a platform for the deposition of graphene and chemically functionalized graphene coatings. This process provides Grafoid with the capability to apply its diverse graphene-based coatings to many different types of material substrates with controllable levels of surface coverage, thickness etc. to meet precise end user requirements.