Image: Jeffrey Fisher
Researchers have demonstrated a new process for rapidly fabricating complex three-dimensional nanostructures from a variety of materials, including metals. The technique uses nanoelectrospray to provide a continuous supply of liquid precursor, which can include metal ions that are converted to high-purity metal by a focused electron beam.
The new process generates structures — such as nanobridges — that would be impossible to make using gas-phase focused electron beam-induced deposition (FEBID) techniques, and allows fabrication at rates up to 5,000 times faster than with the gas-phase technique. And because it uses standard liquid solvents, the new process could take advantage of a broad range of precursor materials.
“By allowing us to grow structures much faster with a broad range of precursors, this technique really opens up a whole new direction for making a hierarchy of complex three-dimensional structures with nanoscale resolution at the rate that is demanded for manufacturing scalability,” said Andrei Fedorov, a professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering.
In the established FEBID process, an electron beam is used to write structures from molecules adsorbed onto a solid surface that provides support and nucleation sites. The precursors are introduced into the high-vacuum electron microscope chamber in gas phase. High-energy electrons in the beam interact with the substrate to produce the low-energy secondary electrons, which dissociate the adsorbed precursor molecules, resulting in deposition of solid material on the substrate surface.
Fedorov and his collaborators have accelerated the original gas-phase process by introducing electrically charged liquid-phase precursors directly into the high vacuum of the electron microscope chamber.
The research was supported by the U.S. Department of Energy’s Office of Science and reported in the journal Nano Letters.
— John Toon