By D. Ian Hopper
WASHINGTON – When two Bell Labs scientists invented the transistor in 1947, it was as tall as the face of a wristwatch. Now, another Bell team has made a transistor from a single molecule – small enough to fit about 10 million on the head of a pin.
“It may become the cornerstone of a new era,” Bell Labs vice president Federico Capasso said.
Scientists predict that silicon transistors, the bedrock element for current computers, are expected to be made as small as physically possible in the second decade of the century. Organic nanotransistors represent a new step for computing that extends beyond that barrier, and can be used in computers on paper, clothes and everywhere else.
“You might think about flexible electronics, some things in which silicon cannot do,” said physicist Hendrik Schon of the Bell three-member team.
The invention by Schon and chemists Zhenan Bao and Hong Meng threatens to make Moore’s Law – the axiom named after an Intel Corp. co-founder who predicted that the number of transistors on a piece of silicon would double roughly every 18 months – a footnote in history.
“I think it will show more or less … the ultimate limit for Moore’s Law,” Schon said.
The breakthrough was published Thursday on the Web site of the journal Science.
Stanford University professor David Goldhaber-Gordon called the invention “really remarkable.”
“It really looks for all the world like a standard silicon transistor, and in some ways even has better parameters,” Goldhaber-Gordon said.
Smaller transistors generally translate to speedier devices. Intel and other chipmakers squeeze millions of transistors on a single microprocessor to power computers, and the techniques needed do to so are very expensive.
Schon said the molecular transistor is cheap to make, and can be done in an ordinary lab rather than the ultra-sanitary “clean room” now used by chipmakers.
Schon’s team used “conjugated molecules” made out of carbon, hydrogen and sulfur. The solution is poured from a beaker onto gold electrodes, and the transistors form by themselves.
The transistor, which Schon called the “ultimate limit for miniaturization,” faces several years of testing and improvements before it can be used in products. Schon and his team also need to figure out how it works.
“There were some pleasant surprises in the observed experimental results,” Schon said. “Now we have to work on getting a better understanding of what’s going on this scale.”
Scientists are taking great strides in organic computing. The last leap was also made by Schon’s team, just a month ago, when they created a transistor out of a cluster of molecules.
In August, IBM researchers created a simple logic circuit on a carbon nanotube, a single-molecule strand of carbon.
Goldhaber-Gordon said researchers have too much invested in silicon to see it replaced by molecular cousins anytime soon, but suggested the new device’s small size would be useful for biological sensors.
“Forty to 50 years of development plus the GNP of a decent sized country will get you quite a lot,” Goldhaber-Gordon said of silicon research.
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