Weaving Miniature Wires from Silicon and Gold.

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CHEMICAL ENGINEERING

Chemical engineers at the University of Texas at Austin have made a breakthrough in the production of far-smaller silicon wires, using revolutionary methods that could lead to development of other new materials with exciting new properties. Silicon wires of this extremely small size will be needed in the construction of the computers of the future and for optoelectronic devices, such as lasers, sensors, computer screens, and other flat-panel displays.

Brian Korgel and Keith Johnston, professors in the Department of Chemical Engineering, have produced silicon "nanowires" using tiny particles of gold suspended under pressure in a compressed fluid at a high temperature. Nanotechnology is derived from nanos, the Greek word for dwarf, and refers to the manipulation of materials on an atomic or molecular scale in order to construct highly miniaturized mechanical devices.

Korgel explains that the electronics industry is reaching the limits of miniaturization and that, "five to 10 years from now, the way we make computer chips will not be able to be scaled down any more. There has been a steady decrease in computer component size because, generally, smaller means faster and more convenient. But they are hitting the end of the road as far as where they can go. They have no idea how they are going to be making the next generation of devices 10 years from now. That's what we're working on."

There are 1,000,000 nanometers in a millimeter. Today's designers are working toward production of computer components that are 100 nanometers long. "We have made components that are four nanometers long, so we are 25 times smaller," Korgel points out.

The researchers produce their nanowires by heating silicon atoms connected to organic molecules until the atoms come loose and form free silicon atoms. This is done in the presence of small clusters of gold atoms referred to as nanocrystals or quantum dots. The quantum dots in this research consist of 100 to 200 atoms of gold. "The gold quantum dots are the seeds that start the growth of silicon nanowires," Johnston notes.

The silicon atoms don't remain free for long, either congregating together or dissolving within the gold quantum...