Nano-Switches Could Yield Even Smaller Gadgets

August 16, 2005

Gadgets seem to get smaller every day, but the silicon-based technology used in most of today's electronics can only get so much smaller.

Now researchers have cooked up tiny Y-shaped tubes of carbon that act like electrical switches. The new tubes could someday become the foundation for ultraminiature electronics.

Conventional carbon nanotubes are hollow, unbranched cylinders of rolled up carbon atoms. These nanotubes, first made in the early 1990s, are more than a thousand times thinner than human hairs and are good electrical conductors.

"Electrons can stream through these nanotubes without any problems," said Apparao M. Rao, a physicist at Clemson University in South Carolina and coauthor of the study. Because the tubes are good at carrying a current, he said, "they're ideal for nano-electronics."

But conductive materials aren't enough to make an electronic gadget work. Any device needs built-in switches to turn currents on and off.

The new carbon nanotubes are shaped like y's and have small metal particles embedded at their junctions. The structure allows researchers to control the flow of electricity through the different branches.

The researchers' findings appear in the September issue of the journal Nature Materials.

Rewriting Moore's Law

Today's commercial electronics use silicon switches called transistors—often millions of them—to control electrical flow.

For decades the number of silicon transistors that engineers have been able to squeeze onto each inch (3 centimeters) of circuitry has roughly doubled every 18 months.

This clockwork-like increase in computing power is called Moore's Law. The law is named after Gordon E. Moore, co-founder of computer chip maker Intel, who made the observation in 1965.

But the law also implies a limit to manufacturers' abilities to scale down electronics. Reducing the bulkiness of silicon transistors has become a challenge. At some point, engineers won't be able to squeeze any more transistors on a chip.

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