Imagine a nanowire?10,000 times thinner than a human hair?that can function as a transistor, a light-emitting diode, a biochemical sensor and many other devices, all along a single “candy-striped” strand.
The practical applications of such technology could include computer chips that are orders of magnitude more dense than today’s best designs. And work at the Ernest Orlando Lawrence Berkeley Laboratory in Berkeley, Calif., is pushing to make this seemingly science-fiction idea become a reality.
Conventional semiconductor devices combine multiple layers of semiconductors, put together much like a sandwich. But the Berkeley Lab is developing a platform for using one-dimensional nanostructures?allowing for far more compact combinations of extremely tiny devices, says Peidong Yang, a chemist with Berkeley Lab’s Materials Science Division. Ultimately, the research could result in computer chips that hold billions?instead of millions?of transistors.
As part of its research, Berkeley Lab recently created striped or “superlatticed” nanowires composed of two different semiconductors: silicon and silicon-germanium alloy. The goal is to be able to place “junctions” on individual wires, with each junction performing a function?such as emitting light or converting energy.
The researchers create the nanowires by heating a gold-plated silicon wafer in a 1-inch furnace to create “nanometer-size” droplets of the materials. They then subject the droplets to a laser that is turned on and off to deposit alternating patterns of gold, silicon and germanium into a superlattice. While it sounds complex, the researchers claim it is actually quite inexpensive and quick?they can reportedly create millions of striped nanowires per hour.
“I believe this will be a technology enabler. It will make other functionalities possible from these semiconductor nanowires in the years to come,” Yang says.