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Researchers Create New Material for Semiconductors Graphene has dazzled scientists, ever since its discovery more than a decade ago, with its unequalled electronic properties, its strength and its light weight. But one long-sought goal has proved elusive: how to engineer into graphene a property called a band gap, which would be necessary to use the material to make transistors and other electronic devices.Now, new findings by researchers at MIT are a major step toward making graphene with this coveted property. The work could also lead to revisions in some theoretical predictions in graphene physics. The new technique involves placing a...

The products of thermally exfoliating graphite oxide to make graphene are much more complex than previously thought, new research shows. The volatile compounds formed vary with reaction conditions, and may influence the graphene’s structure.The most common way to prepare graphene is by thermally reducing – or ‘exfoliating’ – graphite oxide. But the graphene produced often contains defects and lacks the perfect honeycomb structure. One explanation is that these defects may be the result of organic by-products forming and escaping as gases during the reaction.‘It has been commonly believed that the only gaseous products of graphite oxide exfoliation are water, carbon...

FULL TITLE: Solving nearly century-old problem: Using graphene, professor finds out what causes low-frequency electronic 1/f noise =========================================================== A University of California, Riverside Bourns College of Engineering professor and a team of researchers published a paper today that show how they solved an almost century-old problem that could further help downscale the size of electronic devices. The work, led by Alexander A. Balandin, a professor of electrical engineering at UC Riverside, focused on the low-frequency electronic 1/f noise, also known as pink noise and flicker noise. It is a signal or process with a power spectral density inversely proportional to...

Some of the great scientific breakthroughs of the last century came about entirely by accident. Many of you are probably familiar with the origins of the Post It Note, and how it was invented as a result of a failure when attempting to create a super strong adhesive. Well, there may be another such story taking place in the present day. Scientists working with carbon compounds developed Graphene, a safe substance with a lot of structural strength for very little mass and weight. And then some wise guy discovered that it had another use. The recap: Graphene, a very simple...

Atomic structures for three-fold and four-fold coordinated silicon impurities in monolayer graphene © APSA combination of scanning transmission electron microscopy and atomic-resolution spectroscopic techniques has allowed US researchers to pick out individual silicon atoms in a doped graphene sheet. The technique reveals that the silicon atoms can exist in a planar hybridised ‘sp2d’ like form when bonded to four carbon atoms, as well as the anticipated sp3 form when triply coordinated. The experimental observations mesh with simulations of two-dimensional solids and point the way to a method for exploring single impurities in graphene and related materials.Stephen Pennycook and colleagues at...

The graphene framework is not only light, it's flame resistant and mops up oil © Wiley-VCHChemists in China claim to have created the lightest graphene framework to date. The material, which is light enough to rest on a dandelion seed head, is also fire resistant and has record-breaking adsorption and capacitance.The development of ultralight materials has exploded in recent years. Last year, engineers in the US presented a material made of hollow metallic tubes in a micro-lattice. With a density of 0.9mg/cm3, the material was 100 times lighter than styrofoam. Yet that record was beaten in July, when material scientists...

Norwegian researchers are the world’s first to develop a method for producing semiconductors from graphene. This finding may revolutionise the technology industry. The method involves growing semiconductor-nanowires on graphene. To achieve this, researchers “bomb” the graphene surface with gallium atoms and arsenic molecules, thereby creating a network of minute nanowires. The result is a one-micrometre thick hybrid material which acts as a semiconductor. By comparison, the silicon semiconductors in use today are several hundred times thicker. The semiconductors’ ability to conduct electricity may be affected by temperature, light or the addition of other atoms.Fantastic potential Graphene is the thinnest material...

Graphene has attracted enormous attention for radio-frequency transistor applications because of its exceptional high carrier mobility, high carrier saturation velocity, and large critical current density. Herein we report a new approach for the scalable fabrication of high-performance graphene transistors with transferred gate stacks. Specifically, arrays of gate stacks are first patterned on a sacrificial substrate, and then transferred onto arbitrary substrates with graphene on top. A self-aligned process, enabled by the unique structure of the transferred gate stacks, is then used to position precisely the source and drain electrodes with minimized access resistance or parasitic capacitance. This process has therefore...

New research by Columbia Engineering demonstrates remarkable optical nonlinear behavior of graphene that may lead to broad applications in optical interconnects and low-power photonic integrated circuits. With the placement of a sheet of graphene just one-carbon-atom-thick, the researchers transformed the originally passive device into an active one that generated microwave photonic signals and performed parametric wavelength conversion at telecommunication wavelengths."We have been able to demonstrate and explain the strong nonlinear response from graphene, which is the key component in this new hybrid device," says Tingyi Gu, the study's lead author and a Ph.D. candidate in electrical engineering. "Showing the power-efficiency...

A rapid route to synthesise graphene capsules has been developed by researchers in the US and Korea. The capsules can be nano-engineered on demand and show promise in oil absorption. After oil uptake the capsules aggregate on the water surface allowing them to be collected Hollow spheres of graphene or graphene oxide (GO) have previously been made, but usually via complicated routes that involve the assembly of GO sheets onto template particles and then a separate template removal step. Now, a team led by Jiaxing Huang at Northwestern University and HeeDong Jang at the Korea Institute of Geoscience and Mineral...

Physicists in the US have discovered yet another useful property of the wonder material graphene – it can function much like a laser when excited with very short femtosecond light pulses. The team has shown that the material has two technologically important properties – population inversion of electrons and optical gain. The findings suggest that graphene could be used to make a variety of optoelectronics devices, including broadband optical amplifiers, high-speed modulators, and absorbers for telecommunications and ultrafast lasers. Graphene is a sheet of carbon atoms arranged in a honeycomb-like lattice just one atom thick. Since its discovery in 2004,...

Researchers in China and Australia have observed superlubricity – the dropping of friction to near zero – on length scales much larger than before. They say that the phenomenon, which they measured in sheared pieces of graphite, could find applications in sensitive microscopic resonators or nanoscale gyroscopes. Superlubricity is sometimes used to mean simply very low friction, but the original meaning is that the friction between two surfaces disappears almost completely. Proposed in the early 1990s by Motohisa Hirano, then at the Nippon Telegraph and Telephone Corporation in Tokyo, Japan, and others, it relies on a special arrangement of atoms...

The list of remarkable applications for graphene grows ever longer. This time, scientists in the US and Korea have shown that the single-atom thick carbon membrane can be used as a cover slip for an electron microscope to allow atomic-resolution observations of wet chemistry - something that is notoriously tricky to achieve. The graphene cover slip allows researchers to watch liquid chemistry taking place in much greater detail © Image courtesy of Alivisatos, Lee and Zettl research groups, Lawrence Berkeley National Laboratory and KAIST The researchers wanted to investigate how platinum nanocrystals form from solution. 'Seeing the crystals form at...

Stanford scientists have created designer electrons that behave as if they were exposed to a magnetic field of 60 Tesla—a force 30 percent stronger than anything ever sustained on Earth. The work could lead to a revolution in the materials that make everything from video displays to airplanes to mobile phones. "The behavior of electrons in materials is at the heart of essentially all of today's technologies," said Hari Manoharan, associate professor of physics at Stanford and a member of SLAC's Stanford Institute for Materials and Energy Sciences, who led the research. "We're now able to tune the fundamental properties...

Enlarge Image The new graphene. Graphyne may be less famous than graphene, but it could have better electronic properties. Credit: D. Malko et al., Phys. Rev. Lett. (2012) Graphene, a layer of graphite just one atom thick, isn't called a wonder material for nothing. The subject of the 2010 Nobel Prize in physics, it is famed for its superlative mechanical and electronic properties. Yet new computer simulations suggest that the electronic properties of a little-known sister material of graphene—graphyne—may in some ways be better. The simulations show that graphyne's conduction electrons should travel extremely fast—as they do in graphene—but...

Finding could lead to new photodetectors or energy-harvesting devices.Graphene, an exotic form of carbon consisting of sheets a single atom thick, exhibits a novel reaction to light, MIT researchers have found: Sparked by light’s energy, the material can produce electric current in unusual ways. The finding could lead to improvements in photodetectors and night-vision systems, and possibly to a new approach to generating electricity from sunlight. This current-generating effect had been observed before, but researchers had incorrectly assumed it was due to a photovoltaic effect, says Pablo Jarillo-Herrero, an assistant professor of physics at MIT and senior author of a...

Researchers at the University of California, Los Angeles, and one of the largest manufacturers of computer memory, Samsung, have created a new kind of flash memory that uses graphene—atom-thick sheets of pure carbon—along with silicon to store information. Incorporating graphene could help extend the viability of flash memory technology for years to come, and allow future portable electronics to store far more data. Chipmakers pack increasing amounts of data in the same physical area by miniaturizing the memory cells used to store individual bits. Inside today's flash drives, these cells are nanoscale "floating gate" transistors. Recent years have seen the...

A combination of two ordinary materials – graphite and water – could produce energy storage systems that perform on par with lithium ion batteries, but recharge in a matter of seconds and have an almost indefinite lifespan. Dr. Dan Li, of the Monash University Department of Materials Engineering, and his research team have been working with a material called graphene, which could form the basis of the next generation of ultrafast energy storage systems. “Once we can properly manipulate this material, your iPhone, for example, could charge in a few seconds, or possibly faster.” said Dr. Li. Graphene is the...

Cheap solar panels. The most powerful transistors ever. Even the ability to make a fighter jet invisible. Each of these breakthroughs has been announced in the last two weeks. Each relies on one of the most basic elements mined from the earth. And each could line your pockets with cash if you move quickly enough. They all involve a wonder substance called graphene. It’s made from graphite – the same stuff you find in the center of a pencil. Except graphene consists of a single layer of carbon atoms. Let’s hopscotch through these new developments… Researchers in India have discovered...

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