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Scientists make advances on "nano" electronics
2009-02-21
CHICAGO (Reuters) - Two U.S. teams have developed new materials that may pave the way for ever smaller, faster and more powerful electronics as current semiconductor technology begins to reach the limits of miniaturization. One team has made tiny transistors -- the building block of computer processors -- a fraction of the size of those used on advanced silicon chips. Another has made a film material capable of storing data from 250 DVDs onto a surface the size of a coin. Both advances, published on Thursday in the journal Science, use nanotechnology -- the design and manipulation of materials thousands of times smaller than the width of a human hair. Nanotechnology has been hailed as a way to make strong, lightweight materials, better cosmetics and even tastier food. "We have demonstrated that we can make important technologies that are significantly smaller than existing devices," Jeremy Levy of the University of Pittsburgh said in a statement. Levy's team created its nanotech transistors using two ceramic crystal materials known as lanthanum aluminate and strontium titanate. When sandwiched together, these natural insulators conduct electricity as a positive charge is passed across them. Using the tip of an atomic force microscope, Levy's team applied voltage to etch a tiny conducting wire between the two materials, which can later be erased by reversing the charge, much like a child's Etch A Sketch drawing toy. "The transistor we made is arguably the smallest one that has ever been produced in a deterministic and reliable fashion. And we did it using an instrument that can be miniaturized down to the size of a wristwatch," Levy said in an e-mail. He said the same materials can be used to make atom-sized transistors for computers, memory devices and sensors. "In terms of simplicity, it's striking," Alexander Bratkovsky, a scientist for Hewlett-Packard Co who is familiar with the work, said in a statement. THIN FILM Meanwhile, a team from the University of Massachusetts Amherst and the University of California Berkeley said they had found a faster, more efficient way of making a thin semiconductor film that they think could dramatically improve data storage. Many teams have tried to use polymers to create sheets of semiconductor films but the material often lost its structure when spread over large surfaces. To overcome this, the team lead by Thomas Russell of the University of Massachusetts heated sapphire crystals to create a specific pattern of ridges on the surface. This served as a guide for the semiconductor film. "We applied a simple concept to solve several problems at once, and it really worked out," Russell said in a statement. He said the technology could make nearly perfect arrays of semiconductor material that are about 15 times denser than anything achieved previously. "With the densities we describe you could store 250 DVDs on a surface the size of a quarter," Russell said in an e-mail. (Editing by John O'Callaghan)
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