US boffins carve smallest ever nano-particles

US university scientists have developed a new technique that enables the creation of some of the smallest ever metal nanostructures.

The technique, pioneered by physicists at the University of Pennsylvania, allows for the creation of nano-particles less than 10 nanometres across, or 10,000 times smaller than the width of a human hair.

The breakthrough employs transmission electron beam ablation lithography, or Tebal, to 'carve' nanostructures from thin sheets of gold, silver, aluminium and other metals.

According to the boffins, Tebal provides a more dependable method for producing quality versions of these microscopic devices, which are studied for their novel mechanical properties and potential use in next-generation sensors and electronics.

The method also permits simultaneous, real-time atomic imaging of the devices as they are made.

Traditional techniques for building nano-devices employ electron beam lithography but require the use of polymers and chemicals in which the metal is evaporated. Typical results are closer to 50 nanometres in size and rarely as small as 10.

Marija Drndic, professor of physics at the University of Pennsylvania, and her team created nano-disks, nano-rings, nano-wires, nano-holes and multi-terminal nano-transistors.

"Many different approaches have been undertaken to fabricate the small structures needed to probe the phenomena that take place at the nanoscale, but the most widely used and versatile techniques are limited to tens of nanometres, " she said.

"Reliably and consistently fabricating devices at the sub-10 nanometre scale from the top down is generally still challenging, but our technique offers a route to this."

Professor Drndic added that superconducting circuits, magnets and molecule-sized transistors are among the real-world applications that may result from the research.

The results were published in the journal Nano Letters.

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