Researchers at Hewlett-Packard Co. have built molecular-level processors capable of performing basic Boolean functions, thus opening the door for silicon-less electronic devices, possibly as soon as a decade from now.
The molecular processors, part of a larger effort to take the electronics industry beyond the current limitations of Moore's Law, could improve device density by as much as 100 times. They could also serve as a first step toward making logic devices smaller than biological cells, thus providing them with the ability to function as chemical sensors within human blood.
"Using this process, you could build chips far smaller than a speck of dust, possibly just a few microns on a side," notes Phillip J. Kuekes, computer architect and senior scientist at HP Labs.
Kuekes says that the ability to perform basic processing functions on molecular-level devices is a critical step forward for the electronic industry. Up to now, he says, optical lithography techniques have enabled silicon devices to carry on the promise of Moore's Law, which says that transistor-level electronic density will double every two years. But as such devices delve below the level of 15-nanometer linewidths, many experts fear that transistor density will reach its limit, and the doubling effect characterized by Moore's Law will halt. Most believe that halt will occur about 15 years from now.
"By then, current leakage will be such a problem that you won't be able to tell a 'one' from a 'zero' anymore," Kuekes predicts.
That's why HP's recent successes with molecular-level electronics are so critical, experts say. The devices developed at HP Labs use a novel electrochemical technique to carry out basic electronic functions. Rather than a traditional silicon circuit, HP's technique employs a simple grid of metallic nano-wires connected by electronic "switches" just one molecule thick. By applying signals to the molecules trapped between the cross wires, HP researchers created logic gates.
As long ago as 2001, the company's researchers proved that the concept could be applied to the creation of molecular device memories; more recently, the researchers built circuits that add numbers and perform other basic Boolean functions. Ultimately, Kuekes expects adoption of the technology to accelerate as more traditional technologies begin to "run out of steam."
"We can go dramatically smaller than any device built with traditional lithography," he says. "This should carry Moore's Law on for another few decades."
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