Nanotubes grown straight in lar...(miniaturization if researchers can leap ...)

"This would break a logjam for reproducing enough of them in identical form to build into working devices," Liu said of his group's new innovation. "With our technique, their densities are high enough over a large area. And every device would be quite the same, even if thousands or a million of them were made," Liu said.

Researchers have for some time been able to coax nanotubes into growing and extending themselves when primed by a catalyst and provided with a continuous source of carbon delivered in a gas.

But, until now, they have been unable to make them grow straight, long and dense enough in a large enough area to be practical for carrying current on the surfaces of semiconducting wafers, Liu said.

Researchers have also been struggling to control growing nanotubes' tendencies to bend and overlap each other as they extend. Such overlaps would impede a future nanocircuit's performance at high operating speeds, he added.

In 2000, a Liu-led research team at Duke became the first to make long and aligned nanotubes grow on surfaces, though not in a sufficiently parallel and straight way, he said. He has also vied with other groups in growing nanotubes to record lengths.

Recently, other scientific groups developed a way to grow perfectly aligned nanotubes along continuous-and-unbroken "single crystal" surfaces of quartz or sapphire.

One team using that method reported making as many as 10 nanotubes grow within the space of a single micron -- one millionth of a meter -- using iron as a catalyst. They also observed areas with nanotubes as dense as 50 per micron. But such numbers at that density are still "low and not uniform enough for many useful electronic applications," Liu said.

In the new JACS report, Liu's group reports improving on that performance by modifying the method.

Using copper as their growth catalyst and g
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