Jun 24, 2004
Silicon carbide nanoflowers bloom
Researchers at the University of Cambridge, UK, have grown unusual silicon carbide nanostructures. The team’s vapour-liquid-solid process produced nanoflowers, nanotrees and nanobouquets of the material.
“The unique structures will have a range of exciting applications,” said Mark Welland of Cambridge University. “Two that are currently being explored are their use as water-repellent coatings and as a base for a new type of solar cell.”
Welland says water droplets will roll off coatings made from the structures when they are tilted at angles as small as 5°. “This behaviour is a direct consequence of the ability of such nanostructured surfaces to strongly repel water,” he added.
The team grew the structures onto silicon substrates by chemical vapour deposition. They placed gallium nitride powder on the silicon surface and flowed methane over the samples. Under certain temperature and pressure conditions, nanoflowers of silicon carbide formed. The structures had a diameter of 1-2 µm and were 3-5 µm long.
According to the scientists, a typical flower had an intertwined stem, a bulbous head consisting of a tight bundle of nanowires, and a single catalyst particle attached to its top end. The researchers say the high surface-to-volume ratio of the flowers and their complex nanoscale structure mean they’re likely to have physical and chemical properties different from bulk silicon carbide.
Changing the reaction conditions of the process enabled the formation of other types of nanostructure, such as nanobouquets and nanotrees.
The researchers reported their work in the journal Nanotechnology.
About the author
Liz Kalaugher is editor of nanotechweb.org.