Image: Transistor
Hyunwook Song and Takhee Lee
A schematic of a new molecular transistor, which is made up of a benzene molecule linked across gold electrodes.
updated 1/12/2010 1:46:21 PM ET 2010-01-12T18:46:21

The world's smallest transistor, made from a mere six atoms of carbon suspended between two gold electrodes, has been created by scientists from Yale University and South Korea.

Although transistors, which amplify or switch electric signals, are the fundamental building blocks of modern electronic devices, this molecular model is more of a scientific discovery than a technological breakthrough for now. But once such transistors are proven viable, they could help create smaller computer chips for consumer devices that stay cooler by not wasting energy.

In other words, if you're reading this with your computer on your lap — the smaller, efficient transistor could mean your lap stays cool.

The key is not so much the transistor's size, but in how efficiently it transfers energy.

"People always thought the end game was making transistors small," said Mark Reed, a professor at Yale University who helped design the new transistor. "That's really not the problem; it's how much power they dissipate, and one way to modify that is by using different transport devices."

Reed and his colleagues created two molecular transistors: one that worked, and one that didn't work, or at least didn't work very well.

The first transistor, the one that didn't work very well, was made of eight carbon atoms strung together in a line with hydrogen atoms hanging off the sides, like a clothes line with eight wooden pins stuck at even intervals along its length.

This first transistor didn't work well, which the scientists expected; they simply wanted to show they could build a device that small. Electricity traveled along the string, but it took a lot of power to push even a small amount through the alkane string -- too much power to make an efficient transistor.

For the second model, the researchers took six carbon and hydrogen atoms and twisted them into a circle — creating a molecule of benzene. In this form, the electrical current flowed with ease, up one gold electrode, through the carbon atoms, and down the other gold electrode.

Twisting the carbon atoms into a ring brings the carbons electrons closer together, so that the carbon atoms can actually share electrons with each other. Those shared electrons let an electrical current run through with relative ease.

7 award-winning innovations A transistor smaller than one nanometer is a scientific breakthrough, but not a technological one, cautions Reed. "If I take this result and go to IBM and ask what they think, they will answer that its interesting, but it won't help us," said Johnson.

Modern silicon commercial transistors can reach down to about 45 nanometers in size, even smaller in specialized research laboratories. But pack these tiny transistors together and the computer chips can still get hot since energy is being lost during transfer.

Studying new kinds of transistors dissipate heat could produce cooler computers and longer lasting cell phones. These devices are still years away from commercial reality -- of all the benzene transistors Reed and his colleagues created, only about 15 percent of them actually worked. That's a far cry from the reliability of the transistors found in cell phones and computers today.

"Making one is great, showing how it works is fabulous," said James Kushmerick, a scientist at the National Institutes for Standards and Technology. "But you need thousands of them interconnected with a high success rate to create a computer."

The technology to create that many interconnected benzene transistors doesn't exist right now, and likely won't for at least another 10 years, but Kushmerick is still excited about what he calls a "huge scientific breakthrough."

© 2012 Discovery Channel


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