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New molecular chip packs data more tightly than ever

Created by UCLA and Caltech researchers, it has a memory density 20 times silicon circuits' but is not market-ready.

January 27, 2007|Thomas H. Maugh II | Times Staff Writer

UCLA and Caltech researchers have created the densest computer memory chip ever, a device that can comfortably hold the Declaration of Independence yet is only the size of a white blood cell.

The experimental device is nowhere near commercialization, but it demonstrates the potential of molecular manufacturing techniques, which promise to overcome the size limitations of silicon circuitry. Industry experts predict that silicon circuit density will reach the theoretical maximum in 2013, if the pace of increase holds.

The new device has about 100 billion bits of information per square centimeter -- about 20 times the density of current silicon memories. Caltech chemist James Heath, who designed the circuit, said its density could probably be increased 10-fold.

The results were reported Thursday in the journal Nature.

The keys to the device are extremely fine wires fabricated in Heath's laboratory and molecular switches synthesized by UCLA chemist J. Fraser Stoddart.

The switch is a dumbbell-shaped molecule; a ring-shaped chemical around the central rod can be moved from end to end by applying a small electric voltage.

The memory chip itself is a grid of 400 parallel nanowires crosshatched by another 400. At each of the 160,000 intersections, about 100 of the nanoswitches are deposited. Each group of switches serves as a bit that can be switched off or on by the application of a current.

But the researchers still have a long way to go. Only about 30% of the junctions actually work -- although it is possible to program around the defective ones -- and they operate fairly slowly. Moreover, the team has not yet been able to make leads small enough to attach to each of the 800 wires.

Nonetheless, Heath said, all of these problems are potentially solvable.

"Whether it is actually possible to get this new memory circuit into a laptop, I don't know," he said.

"But we have time."

thomas.maugh@latimes.com

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