SCIENTISTS invent transistor made of single molecule, a breakthrough in computing technologies

Friday, November 9th 2001, 12:00 am
By: News On 6

WASHINGTON (AP) _ 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.

``This work pushes the miniaturization of electronics to its final frontier,'' Bell Labs vice president Federico Capasso said.

Scientists predict that silicon transistors, the bedrock element for current computers, will 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 three-member Bell 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.

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 thousands of molecules working in tandem.

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.

Not only are the transistors smaller _ each one-billionth of a meter long _ and faster, but they are cheaper to make than silicon types.

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.

The method also will help scientists to learn how electricity travels on such a small scale. Already, they can see that electricity moves through one molecule but not through an adjoining one used as a casing.

``That already shows that conductance really depends on the details of the molecular structure,'' Goldhaber-Gordon said. ``We probably don't understand the physics of conduction molecules so well.''

Goldhaber-Gordon said he doubted organic transistors would replace silicon, to see it replaced by molecular cousins anytime soon, due to the investment in silicon research. ``Forty to 50 years of development plus the GNP of a decent sized country will get you quite a lot,'' he said.