LOUISVILLE, Ky. – University of Louisville chemical engineer Mahendra Sunkara, doctoral student Shashank Sharma and their research group have developed a process for growing nanometer-scale wires that allows them to control more easily the minute wires’ size, structure and composition.
The ultrasmall structures are one-thousandth the size of a human hair. Nanowires have potential in the growing research realm of nanotechnology and could be applied to nanoelectronics, sensors, fuel cells, solar devices, catalysis, solid-state-based refrigeration, anti-bioterrorism and lightweight, advanced military and space gear and apparel.
The group’s technique is novel because it uses pools or thin films of low-melting metals such as gallium to create the structures and uses gas-phase chemistry to control the size of the structures. Previously, scientists have assumed gold or iron clusters are needed to make a pattern for one-dimensional growth of materials, Sunkara said.
The process allows the scientists to grow nanowires in bulk quantities.
The research team grows crops of nanowires by spreading a thin film of molten gallium on a solid surface and exposing it to a gas in an excited state; by controlling the chemistry in a reactor, the group can form multiple nuclei that grow into multiple wires.
The group has demonstrated its process with silicon, carbon, gallium oxide and gallium nitride nanowires. U of L filed an application for a broad process patent in June 2000. Sunkara and his colleagues also published their results on silicon nanowires in the Sept. 3, 2001, Applied Physics Letters journal. They reported their results on other materials in the Proceedings of the Materials Research Society’s spring 2001 and fall 2001 meetings, and they will give November presentations at annual meetings of the society and the American Institute of Chemical Engineers.
For information and photos, contact Sunkara at (502) 852-1558 or mahendra@louisville.edu.