Wires just a few nanometers thick are among the technologies that could lead to improvements in memory chips and high-resolution displays. The challenge, however, has been to assemble nanowires in regular patterns in order to build large numbers of devices such as transistors or diodes on a single chip. Babak Nikoobakht of the National Institute of Standards and Technology in Gaithersburg, Md., has now managed to grow nanowires exactly where they're needed.
Nikoobakht first placed an orderly array of gold nanodroplets on a sapphire crystal surface. He then exposed the droplets to a hot gas of zinc oxide. The droplets acted as catalysts, each one spawning the growth of a zinc oxide crystal just 10 or 15 nm across.