Scientists Strive to Replace Silicon with Graphene on Nanocircuitry
In a technique known as thermochemical nanolithography, the tip of an atomic force microscope uses heat to turn graphene oxide into reduced graphene oxide, a substance that can be used to produce nanocircuits and nanowires with controllable conductivity. (University of Illinois at Urbana-Champaign)
Scientists have made a breakthrough toward creating nanocircuitry on graphene, widely regarded as the most promising candidate to replace silicon as the building block of transistors. They have devised a simple and quick one-step process based on thermochemical nanolithography (TCNL) for creating nanowires, tuning the electronic properties of reduced graphene oxide on the nanoscale and thereby allowing it to switch from being an insulating material to a conducting material.
The technique works with multiple forms of graphene and is poised to become an important finding for the development of graphene electronics. The research appears in the June 11, 2010, issue of the journal Science.
Scientists who work with nanocircuits are enthusiastic about graphene because electrons meet with less resistance when they travel along graphene compared to silicon and because today’s silicon transistors are nearly as small as allowed by the laws of physics. Graphene also has the edge due to its thickness - it’s a carbon sheet that is a single atom thick. While graphene nanoelectronics could be faster and consume less power than silicon, no one knew how to produce graphene nanostructures on such a reproducible or scalable method. That is until now.
“We’ve shown that by locally heating insulating graphene oxide, both the flakes and epitaxial varieties, with an atomic force microscope tip, we can write nanowires with dimensions down to 12 nanometers. And we can tune their electronic properties to be up to four orders of magnitude more conductive. We’ve seen no sign of tip wear or sample tearing,” said Elisa Riedo, associate professor in the School of Physics at the Georgia Institute of Technology. (more…)
Layered Graphene Sheets Could Solve Hydrogen Storage Issues
A graphene-oxide framework (GOF), formed of layers of graphene connected by boron-carboxylic “pillars.” GOFs such as this one are just beginning to be explored as a potential storage medium for hydrogen and other gases. (NIST)
Graphene—carbon formed into sheets a single atom thick—now appears to be a promising base material for capturing hydrogen, according to recent research* at the National Institute of Standards and Technology (NIST) and the University of Pennsylvania. The findings suggest stacks of graphene layers could potentially store hydrogen safely for use in fuel cells and other applications.
Graphene has become something of a celebrity material in recent years due to its conductive, thermal and optical properties, which could make it useful in a range of sensors and semiconductor devices. The material does not store hydrogen well in its original form, according to a team of scientists studying it at the NIST Center for Neutron Research. But if oxidized graphene sheets are stacked atop one another like the decks of a multilevel parking lot, connected by molecules that both link the layers to one another and maintain space between them, the resulting graphene-oxide framework (GOF) can accumulate hydrogen in greater quantities.
Inspired to create GOFs by the metal-organic frameworks that are also under scrutiny for hydrogen storage, the team is just beginning to uncover the new structures’ properties. “No one else has ever made GOFs, to the best of our knowledge,” says NIST theorist Taner Yildirim. “What we have found so far, though, indicates GOFs can hold at least a hundred times more hydrogen molecules than ordinary graphene oxide does. The easy synthesis, low cost and non-toxicity of graphene make this material a promising candidate for gas storage applications.” (more…)
A Huge Step Toward Mass Production of Graphene
This graphic represents an atom-thin sheet of graphene, a form of carbon that could replace silicon in future electronic devices. Scientists have developed a simple manufacturing method that could allow its mass production. (Credit: Wikimedia Commons)
Scientists have leaped over a major hurdle in efforts to begin commercial production of a form of carbon that could rival silicon in its potential for revolutionizing electronics devices ranging from supercomputers to cell phones. Called graphene, the material consists of a layer of graphite 50,000 times thinner than a human hair with unique electronic properties. Their study appears in ACS’ Nano Letters, a monthly journal.
Victor Aristov and colleagues indicate that graphene has the potential to replace silicon in high-speed computer processors and other devices. Standing in the way, however, are today’s cumbersome, expensive production methods, which result in poor-quality graphene and are not practical for industrial scale applications.
Aristov and colleagues report that they have developed “a very simple procedure for making graphene on the cheap.” They describe growing high-quality graphene on the surface of commercially available silicon carbide wafers to produce material with excellent electronic properties. It “represents a huge step toward technological application of this material as the synthesis is compatible with industrial mass production,” their report notes.
Download full text article here: http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/nl904115h
Researchers Find Better Way to Manufacture Fast Computer Chips
By Pam Frost Gorder
“Graphene has huge potential -- it’s been dubbed ‘the new silicon,’” said Padture, who is also director of Ohio State’s Center for Emergent Materials.
Engineers at Ohio State University are developing a technique for mass producing computer chips made from the same material found in pencils.
Experts believe that graphene — the sheet-like form of carbon found in graphite pencils — holds the key to smaller, faster electronics. It might also deliver quantum mechanical effects that could enable new kinds of electronics.
Until now, most researchers could only create tiny graphene devices one at a time, and only on traditional silicon oxide substrates. They couldn’t control where they placed the devices on the substrate, and had to connect them to other electronics one at a time for testing.
In a paper published in the March 26 issue of the journal Advanced Materials, Nitin Padture and his colleagues describe a technique for stamping many graphene sheets onto a substrate at once, in precise locations. (more…)
MIT: New Material Could Lead to Faster Chips
EECS assistant professors Tomás Palacios, left, and Jing Kong examine oscilloscope traces showing the doubling in frequency of an electromagnetic signal processed through their experimental graphene microchip. (Photo Donna Coveney/ Courtesy of MIT)
New research findings at MIT could lead to microchips that operate at much higher speeds than is possible with today’s standard silicon chips, leading to cell phones and other communications systems that can transmit data much faster.
The key to the superfast chips is the use of a material called graphene, a form of pure carbon that was first identified in 2004. Researchers at other institutions have already used the one-atom-thick layer of carbon atoms to make prototype transistors and other simple devices, but the latest MIT results could open up a range of new applications.
The MIT researchers built an experimental graphene chip known as a frequency multiplier, meaning it is capable of taking an incoming electrical signal of a certain frequency — for example, the clock speed that determines how fast a computer chip can carry out its computations — and producing an output signal that is a multiple of that frequency. In this case, the MIT graphene chip can double the frequency of an electromagnetic signal. (more…)
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