5 tech breakthroughs: Chip-level advances that may change computing

Laser-connected chips, flexible printed circuits, memristors and more are on the horizon.

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From soot to circuits: Graphene

For the past 45 years, almost like clockwork, the number of transistors on a state-of-the-art silicon computer chip has roughly doubled every two years, making Moore's Law as reliable as the law of gravity. As the active elements on a chip have gotten smaller and cheaper to make, more of them could be shoehorned into devices of increasing complexity, ability and power -- all at roughly the same cost as the previous generation of products.

This embarrassment of digital riches may at last be heading toward a dead end. Scientists trying to stuff ever more transistors onto a silicon chip are having trouble reliably making active elements smaller than the current best of 14 nm -- roughly double the size of a hemoglobin molecule in blood or about one-thousandth the size of a grain of talcum powder.

graphene under microscope
Graphene is a single-atom-thick layer of carbon arranged in a honeycomb pattern.

A substance called graphene could breathe new life into Moore's Law by augmenting silicon technology. Made from nothing more glamorous than soot, graphene is an atom-thick layer of carbon atoms arranged in a hexagonal pattern. Under an electron microscope, graphene looks like a cross between chicken wire and a honeycomb.

"It not only looks strange but has incredible properties," says Walt de Heer at his nanoscience lab at the Georgia Institute of Technology. "Graphene is a wonderful material to make electronics out of," he says. "It's fast, doesn't use a lot of power and can be made with very small features. It outperforms silicon and does things silicon can't. It could be the future of electronics."

Semiconductor researchers have been experimenting with graphene since the 1970s but have had problems making ultrathin layers of the honeycomb. University of Manchester researchers Andre Geim and Konstantin Novoselov successfully produced graphene layers in 2004 (this and other advances in graphene research earned them the 2010 Nobel Prize in physics), and the field has advanced rapidly since then.

Earlier this year, de Heer's group fabricated graphene wires -- an essential first step in making microchips -- that were about 10 nm wide by using epitaxy to deposit a sheet of pure graphene onto a silicon chip. (Epitaxy is the process of growing a thin crystalline layer on the surface of another crystal so that the layer mimics the structure of the substrate.)

Eventually, electronic structures as small as 1 nm and much faster than silicon are possible, de Heer says. "If it pans out, graphene could yield a terahertz processor," he predicts -- roughly 20 times faster than today's best silicon chip.

Walt de Heer, Georgia Tech
Georgia Tech's Walt de Heer: "If it pans out, graphene could yield a terahertz processor."

Next year, the Georgia Tech group hopes to finish work on a prototype graphene integrated circuit to use as a test bed for exploring the material's unique properties and refining the technology for creating circuits.

Meanwhile, researchers at IBM have produced experimental graphene-based transistors and integrated circuits using standard semiconductor manufacturing techniques. IBM's Guha points to these as the first steps toward graphene being used on an industrial scale.

"This area has great potential," he says. "It has applications in military and wireless technology and the possibilities for integration with silicon. What is needed now is a lot of hard work to demonstrate the ability to build amplifier circuits and to create large areas of high-quality graphene active circuits integrated in them."

While the first graphene products could appear in the 2013 time frame, don't expect to see super-fast laptops powered by graphene chips anytime soon. Because of their expense, they are likely to show up initially for specialty uses where cost doesn't matter as much as top speed and low power use.

Similarly, integrated circuits that seem rudimentary today were once expensive specialty items used in military and space applications where cost wasn't the main consideration. "The history of this area," says NIST's Seiler, "is that these things start out expensive and rare and become inexpensive and everywhere."

HP Labs' Williams adds, "It's like creating a new way of making chips that could be a lot faster. Graphene has a lot of potential and could be in everyday items in 10 years."

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