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According to a press release, a Cornell research team has invented a simple way to grow graphene directly onto a silicon wafer. The work was published online Oct. 27 in the journal Nano Letters.

Predictions have been made that graphene will eventually be a substitute for silicon in electronics, but making it in large quantities is a challenge. Scientists have made progress since the days when they used scotch tape to pull off a layer of graphene from graphite, but most contemporary methods aren’t yet robust enough for large-scale manufacturing, especially for the applications that require graphene with varying numbers of layers at random positions.

“You can imagine trying to peel a piece of shrink wrap off a dish to put it on a new dish - it’s going to be messy,” said lead researcher Jiwoong Park, Cornell assistant professor of chemistry and chemical biology.

The Cornell group’s new method is to grow the graphene directly onto silicon wafers coated with a special evaporated copper film. They then cut the graphene films into their desired shapes using such standard methods as photolithography. Finally, they move the underlying copper with a chemical solution. What is left is a graphene film that draped down over the silicon wafer with little defect.

“Once the graphene is made on top of this wafer, you can apply any thin-film processing technique,” Park said.

The team is now experimenting with growing four-inch wafers, which would further demonstrate the manufacturing potential of graphene-based electronics.

I don’t know much about this other than what was posted at PNNL’s website last week, but I hope to see something published on this soon:

Researchers would like to develop lithium-ion batteries using titanium dioxide, an inexpensive material. But titanium dioxide on its own doesn’t perform well enough to replace the expensive, rare-earth metals or fire-prone carbon-based materials used in today’s lithium-ion batteries. To test whether graphene, a good conductor on its own, can help, PNNL’s Gary Yang and colleagues added graphene, sheets made up of single carbon atoms, to titanium dioxide. When they compared how well the new combination of electrode materials charged and discharged electric current, the electrodes containing graphene outperformed the standard titanium dioxide by up to three times. Graphene also performed better as an additive than carbon nanotubes. Yang discussed this work and provided an overview of the field of electrical storage materials.

Just for the record, it appears from a note on the website that ACerS member Jun Liu partnered with Yang on this research. Yang recently spoke at Oregon State University’s “Micro Nano Breakthrough Conference” held last week in Portland, Ore.

When half of the hydrogen in this graphane (fully hydrogenated graphene) sheet is removed, the resulting "graphone" becomes a ferromagnetic semiconductor with a small indirect gap. (Credit: Nano Letters/ Puru Jena/VCU.)

A team of researchers at Virginia Commonwealth University reports that it has designed a new graphite-based, magnetic nanomaterial that acts as a semiconductor and could help material scientists create the next generation of electronic devices and microchips.

The researchers used theoretical computer modeling to design the new material they called graphone, derived from graphene. (Check out this recent CTT blog post for a video of scientists making graphene out of graphite.)

The ability to make graphene magnetic adds to its potential for novel applications in spintronics. Spintronics are a family of memory and data processing devices that exploit electron spin.

Although graphene’s properties can be significantly modified by introducing defects and by saturating with hydrogen, it has been very difficult for scientists to manipulate the structure to make it magnetic.

“The new material we are predicting – graphone – makes graphene magnetic simply by controlling the amount of hydrogen coverage – basically, how much hydrogen is put on graphene. It avoids previous difficulties associated with the synthesis of magnetic graphene,” said Puru Jena, distinguished professor in the VCU Department of Physics.

“One of the important impacts of this research is that semi-hydrogenation provides us a very unique way to tailor magnetism. The resulting ferromagnetic graphone sheet will have unprecedented possibilities for the applications of graphene-based materials,” says Qiang Sun, research associate professor with the VCU team.

A paper on the team’s research appears online in the journal Nano Letters.

Interestingly, VCU announced a few weeks ago that beginning in 2010, it would offer an interdisciplinary doctoral degree program in nanoscience and nanotechnology, making VCU the first major research university in the state to offer such a program, and one of only a handful of programs in the United States.

Scientists worldwide are probably hitting their heads wondering, “Why didn’t I think of this!”

The idea for a simple new process came in a burst of inspiration: Can a camera flash instantly heat up graphite oxide and turn it into graphene?

Researchers simply hold a consumer camera flash over the graphite oxide and, a flash later, the material is now a piece of fluffy graphene. Awesome!

Previous processes to reduce graphite oxide relied on toxic chemicals or high-temperature treatment.

The process, discovered by Jiaxing Huang, assistant professor of materials science and engineering at Northwestern’s McCormick School of Engineering and Applied Science, and his graduate student Laura Cote, was published in the Aug. 12 issue of the Journal of the American Chemical Society.

Check it out:

(Abbreviations fixed - h/t to reader Bob Gottschall)

The use of graphene as a full-function transistor is a step closer.  A team at the Berkeley National Lab led by Feng Wang has figured out a way to create a bandgap in bilayer graphene that can be precisely controlled from 0 to 250 milli-electron volts at room temperature. This is a smaller bandgap than typical semiconductors and could open the door to new kinds of optoelectronic devices for working with and detecting infrared light, including nano-LEDs.

Heretofore, single layer graphene’s lack of a bandgap has limited its potential in electronic applications. In a LBL press release, Wang said, “You can build field-effect transistors with graphene, but if there’s no bandgap you can’t turn them off! If you could achieve a graphene bandgap, however, you should be able to make very good transistors.”

Wang’s approach is to induce a bandgap by applying an electrical field between two layers of graphene, i.e., bilayer graphene. In 2006, the group had found a way to create a crude bandgap by doping bilayer graphene with metal atoms. The bandgap, however, was uncontrollable and of little practical use. After coming across some theoretical work about the use of an electrical field, they decided to focus on using that approach.

They went on to build a dual-gated field-effect transistor device with an independently adjustable bandgap. This two-gated device can controls the flow of electrons from a source to a drain with electric fields shaped by gate electrodes. Wang’s group used a silicon substrate as the bottom gate with an insulating layer of silicon dioxide between it and the stacked graphene layers. It was topped off with sapphire on the graphene bilayer and a top gate of platinum. In essence, all of these layers were transparent.

The group shined a synchrotron light beam generated at LBL’s Advanced Light Source facility through the nano-FET. Wang and the other researchers discovered that as they tuned the electrical fields (by varying the voltage of the gate electrodes), they could detect changes in the light absorbed by the gated graphene layers. IR spectrographic measurements of the absorption peak provide a measurement of the bandgap that could be mapped against each change in gate voltage.

Wang and his colleagues work is published in the June 11 issue of Nature.

Adding . . . the work was funded by DOE’s Office of Science, Office of Basic Energy Sciences.