Gold Nanoparticles can be used to make straight v-shaped nanochannels a few nanometers across for next generation computer chips and devices

Scientists from the National Institute of Standards and Technology (NIST) and IBM have a new “self-assembly” methods that researchers aim to harness for making useful devices.

Foreseeable applications include integrating lasers, sensors, wave guides and other optical components into so-called lab-on-a-chip devices now used for disease diagnosis, screening experimental materials and drugs, DNA forensics and more. Easy to control, the new gold-catalyzed process for creating patterns of channels with nanoscale dimensions could help to spawn entirely new technologies fashioned from ensembles of ultra-small structures.

Preliminary research results that began as lemons—a contaminant-caused failure that impeded the expected formation of nanowires—eventually turned into lemonade when scanning electron microscope images revealed long, straight channels.

“We were disappointed, at first,” says NIST research chemist Babak Nikoobakht. “Then we figured out that water was the contaminant in the process—a problem that turned out to be a good thing.”

That’s because, as determined in subsequent experiments, the addition of water vapor served to transform gold nanoparticles into channel diggers, rather than the expected wire makers. Beginning with studies on the semiconductor indium phosphide, the team teased out the chemical mechanisms and necessary conditions underpinning the surface-etching process.

Electron micrograph of surface-directed nanochannels formed on the surface of the semiconductor indium phosphide. Nanochannels are formed using a gold-catalyzed vapor-liquid-solid etch process and their locations are defined by the deposited gold pattern. Credit: Marti/JILA