October 27, 2008

New Way Found to Make, Pattern Nanowires

U.S. scientists say they have developed a method that makes and patterns nanoscale wires and other devices now made with expensive lithographic tools.

"You can, in principle, build almost any types of architectures you want at nanoscale," said Cornell University Associate Professor Dan Luo and postdoctoral researcher Wenlong Cheng.

They said they began with gold nanoparticles about 12 nanometers in diameter suspended in water. To suspend metal particles in water, the researchers coated them with a "ligand" that adheres to the metal and to water. A second innovation in the Cornell process is to use single chains of synthetic DNA as the ligand.

The scientists said the DNA molecules extend from the particle-like hairs and, as the water evaporates, entangle the particles with one another. Adjusting DNA lengths can precisely control the distance between the particles to make them assemble into orderly arrays called superlattices that have applications in computer memory and photonics and have unique properties in electronic circuits.

The new process means nanoscale superlattice features -- currently possible only with expensive, specialized equipment -- can be made in an inexpensive way.

The work is detailed in the journal Nature Nanotechnology.