‘Spincasting’ to offer cheaper nanoparticle thin films?

Spincasting, which utilises centrifugal force to distribute a liquid onto a solid substrate, is already used in the electronics industry to deposit organic thin films on silicon wafers to create transistors. For this study, however, the researchers first dispersed magnetic nanoparticles coated with ligands, small organic molecules that bond directly to metals, into a solution to facilitate the even distribution of the nanoparticles in it and, later, on the substrate itself. A drop of the solution was then placed on a silicon chip that had been coated with a layer of silicon nitride. The chip rotated at high speed to spread the nanoparticle solution over the surface of the chip and, as it dried, a thin layer of nanoparticles was left on the surface of the substrate. Using this technique, the researchers were able to create an ordered layer of nanoparticles on the substrate over an area covering a few square microns. "The results are promising and this approach definitely merits further investigation," said Dr Joe Tracy, an assistant professor of materials science and engineering at NC State. "One benefit of spincasting is that it is a relatively quick way to deposit a layer of nanoparticles. It also has commercial potential as a cost effective way for creating nanoparticle thin films." Although Dr Tracy maintained his excitement about the technique, he admitted there were still several hurdles to overcome. "Modifications to the technique are needed so that it can be used to coat a larger surface area with nanoparticles," he said. "Additional research is also needed to learn how, or whether, the technique can be modified to achieve a more even distribution of nanoparticles over that surface area."