THE GOLD NUGGETS BEING EXTRACTED BY these Purdue University researchers (picture) are far too tiny to be seen by the naked eye. But they could be pay dirt for chipmakers in the future. Each contains only about 500 atoms of gold. It would take a string of 250,000 of these nanonuggets to span the head of a pin.
The nuggets are so small that an electrical current can exist only in the form of a single electron passed off from one nugget to the next. For the chip industry, single-electron signal flows are the ultimate dream: Nothing could be smaller. "We're working hard on ways of making logic and memory circuits," says team member Ronald P. Andres, a professor of chemical engineering at Purdue.
He's confident of eventual success because the technology--and the challenges ahead--are fairly straightforward. The nuggets are precipitated from gaseous gold and wrapped in organic molecules, then dissolved in a solvent. The mixture is painted on a silicon wafer. The solvent evaporates, and the nanoclusters form an ultrathin conducting film.
The Purdue University researchers' next goal is to control the self-assembly process to produce circuit lines instead of a film. The research has already sparked interest from chipmakers, especially in Japan, says Andres. "But we've got a lot of work to do before we can make millions of chips."