The slimmer copper nanorods were formed by periodically interrupting the growth process. The vapor-deposition process was occasionally halted, and the fledgling nanorods were exposed to oxygen. This resulted in a forest of nanorods with diameters between 10 nanometers and 50 nanometers far smaller than the typical 100-nanometer diameter copper nanorods grown conventionally without interruption.
Vast forests, or arrays, of copper nanorods are produced by vapor deposition at an oblique angle. In a conventional setting, with an uninterrupted stream of copper atoms deposited in a vacuum onto a substrate, the deposition angle naturally results in taller, thicker nanorods.
Periodically interrupting the deposition, and exposing the copper nanorods to ambient air, however, leads to oxygen being absorbed into the surface of the nanorods. During subsequent depositions, this oxidized copper helps to prevent the vaporized copper atoms from migrating away from the very tips of the nanorods. This ensures the nanorods grow taller, without necessarily growing in diameter. The more growth interruptions, the thinner the resulting nanorods, Wang said.
Wang and the research group have filed for a patent for this new technology. The patent is currently pending.
|Contact: Michael Mullaney|
Rensselaer Polytechnic Institute