TechFront New Developments in Manufacturing and Technology
DOE Grant Funds Research to Improve Nanoscale Additive Manufacturing
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new three-year $660,000 grant from the US Depart- ment of Energy (DOE) will fund researchers at the Georgia Institute of Technology (Atlanta) on develop- ment of advanced additive manufacturing techniques used to create 3D nanoscale structures.
The research will use a technique employing high-speed, thermally energized jets in delivering precursor materials and inert gas that dramatically accelerates growth while improv- ing the purity and increasing the aspect ratio of the 3D structures. Known as focused electron beam induced depo- sition (FEBID), this technique delivers a tightly-focused beam of high-energy electrons and an energetic jet of thermally excited precursor gases, both confined to the same spot on a substrate.
Secondary electrons generated when the electron beam strikes the substrate cause decomposition of the precursor molecules, forming nanoscale 3D struc- tures whose size, shape and location can be precisely controlled, according to the researchers. The gas-jet-as- sisted FEBID technique allows fabrication of high-purity nanoscale structures using a wide range of materials and combination of materials.
“This unique nanofabrication approach opens up new opportunities for on-demand growth of structures with high aspect ratios made from high-purity materials,” said Andrei Fedorov, a professor in Georgia Tech’s Woodruff School of Mechanical Engineering and the project’s leader. “By providing truly nanoscale control of geometries, it will impact a broad range of applications in nanoelectronics and biosensing.” The researchers have demonstrated the feasibility of the technique, and expect the grant to help them develop an understanding of how the process works, accelerate the rate of materials growth and provide improved control over the pro- cess. The research will include both theoretical modeling and experimental evaluation. Proof of principle for using the jets as part of the FEBID technique was reported by Fedorov’s group in the journal Applied Physics Letters in 2011.
A heated capillary micro-nozzle is shown installed on the deposi- tion stage of a focused electron beam induced deposition (FEBID) system, along with the test chip used for electrical characterization of deposits for graphene interconnects.
“Wherever electrons strike the surface, you can grow the deposit,” explained Fedorov. “That provides a tool for growing complex three-dimensional structures from a variety of materi- als with resolution at the tens of nanometers. Electron beam in- duced deposition is much like inkjet printing, except that it uses electrons and precursor molecules in a vacuum chamber.” Major challenges lie ahead for using the technique to manufacture 3D nanostructures including increasing the rate of deposition and eliminating the unwanted deposits of carbon that are formed as part of the process. Fedorov and his team
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By allowing the rapid atom-by-atom “direct writing” of materials with controlled shape and topology, the work could lead to a nanoscale version of the 3D printing processes now revolutionizing fabrication of structures at the macro scale. The technique also could be used to produce nano-electro- mechanical sensors and actuators, to modify the morphology and composition of nanostructured optical and magnetic materials to yield unique properties, and to engineer high- performance interconnect interfaces for graphene and carbon nanotube-based electronic devices.
Photo courtesy Rob Felt, Georgia Tech
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