Lianne Milton for The New York Times  THE NEW CIRCUIT Max Shulaker and colleagues grow billions of carbon nanotubes on a quartz surface.  STANFORD, Calif. — In a cluttered chip-making laboratory on Stanford’s campus, Max Shulaker is producing the world’s smallest computer circuits by hand.  Mr. Shulaker, a graduate student in electrical engineering, is helping to pioneer an extraordinary custom manufacturing process: making prototypes of a new kind of semiconductor circuit that may one day be the basis for the world’s fastest supercomputers — not to mention the smallest and lowest-powered consumer gadgets.  If the new technology proves workable, it will avert a crisis that threatens to halt more than five decades of progress by chip makers, who now routinely etch circuits smaller than a wavelength of light to make ever more powerful computers.  Even light waves, it turns out, have their limits. In an industry renowned for inventions both radical and resourceful, designers are in urgent need of new ways to make circuits smaller, faster and cheaper.  This year Intel, the world’s largest chip maker, introduced a 3-D transistor that pushes a thin pillar out of the plane of the silicon surface, in an effort to accommodate billions of tiny switches on a single microprocessor.  That approach is controversial; the challenge is not just to squeeze in more switches but to get them to turn on and off quickly and cleanly, and many people in the industry believe there are less drastic ways to do that.  And whichever approach proves most effective, there is a growing consensus among engineers and industry executives that silicon’s days are numbered. On the horizon is an even smaller manufacturing world, nanoelectronics, that will be characterized by the ability to build circuits on a molecular scale.  So at universities and corporate laboratories around the world, researchers are trying to develop the next generation of chip-making technologies.  Mr. Shulaker is a member of the Robust Systems Group at Stanford, led by Subhasish Mitra, a former Intel engineer. The new switch he and other student researchers are making is called a carbon nanotube field effect transistor, or C.N.F.E.T.  To make prototype switches, Mr. Shulaker first chemically grows billions of carbon nanotubes — each only about 12 atoms wide — on a quartz surface. He coats them with an ultrafine layer of gold, and then uses a piece of tape — much like a lint remover — to pick them up by hand and transfer them gently to a silicon wafer.  The difference is that for the first time circuits are not etched with light waves; rather, they are at least partly “self-assembling.” The ultrafine wires made from carbon nanotubes are being laid down using a chemical process as the first step in making a computer circuit.  What results are nanocircuits that are far smaller and use far less power than today’s most advanced silicon-based computer circuits.  With the light-etching method, the smallest part of a semiconductor is currently 32 nanometers, and the nanotechnology is an approach that both Intel and I.B.M. have high hopes for by the time semiconductor parts are down to seven nanometers — which could be as early as 2017.  “We’re exploring this very seriously,” said Supratik Guha, director of physical sciences at I.B.M.’s Thomas J. Watson Research Laboratory. “We feel that if we can place carbon nanotubes a couple of nanometers apart, they will outperform silicon.”  The idea of scaling down electronic circuits goes back at least to 1960, when a young electrical engineer named Douglas Engelbart spoke at a radio and electronics technical conference in Philadelphia. Dr. Engelbart had hit on the idea that shrinking the basic circuitry of the first digital computers could lead to a drastic increase in power.  “Boy, are there going to be some surprises over there,” he told his audience.  It turned out to be an understatement.
As silicon processors grow more packed with each generation, they lose efficiency, and researchers are looking for a new medium.