Oct 19, 2016 | By Benedict
Researchers at Vienna University of Technology (TU Wien) have discovered a way to 3D print pure gold nanostructures using FEBID, a form of additive direct-write lithography. The work could offer a promising new way for manufacturers to create gold devices.
Typical impure FEBID gold (a), compared with FEBID gold produced using new method (b)
Gold is considered a valuable material mainly thanks to its use in expensive jewelry, ornaments, and other luxury goods. However, the metal is also highly desirable when making functional nanostructures. Patterned gold nanostructures are key components in plasmonic devices, in biosensors with immobilized antibodies, and as electrical contacts. Until now, however, gold nanostructures have been predominantly 2D, produced using resist-based lithography techniques. Researchers at TU Wien, under the leadership of by Dr. Heinz Wanzenboeck, have found a way to fabricate 3D printed gold nanostructures, using focused electron beam induced deposition (FEBID). Their findings have been published in Scientific Reports.
FEBID is a method of fabricating custom 2D and 3D nanostructures in a single process, without the use of masks or resists. In the process, the focused electron beam of an electron microscope is used to decompose a metalorganic precursor, functioning like a nanoscale 3D printer with a resolution of 1 nanometer. Unfortunately, the electron-induced decomposition of metalorganic precursors typically yields metals with high carbon contaminations; the goal of Wanzenboeck and the TU Wien team was to produce gold with much higher levels of material purity.
While conventional FEBID gold deposition usually contains about 70 atomic percent carbon and only 30 atomic percent gold, the new approach developed at TU Wien permits the fabrication of pure gold structures through the in situ addition of an oxidizing agent during the gold deposition. “The whole community was working hard for the last 10 years to directly deposit pure gold nanostructures,” said Wanzenboeck. “It’s a bit like discovering the legendary philosopher’s stone that turns common, ignoble material into gold.”
This deposited pure gold structure exhibits extremely low resistivity, close to that of bulk gold. By way of contrast, a FEBID gold structure typically has a resistivity of around 1-Ohm-cm, about one million times worse than that of the purest bulk gold. The specially enhanced FEBID process produces a resistivity of 8.8 micro-Ohm-cm, just a factor of four away from that of the purest gold (2.4 micro-Ohm-cm).
Typical FEBID gold (c), new FEBID gold (d)
According to the researchers, the implications of the new technique could be significant and far-reaching, particularly in the field of nanoplasmonics and bioelectronics devices. “This highly conductive and pure gold structure will open a new door for novel nanoelectronic devices,” commented Dr. Mostafa Moonir Shawrav and Dipl.Ing. Philipp Taus, both authors on the paper. “For example, it will be easier to produce pure gold structures for nanoantennas and biomolecule immobilization which will change our everyday life.”
The researchers' paper, titled “Highly conductive and pure gold nanostructures grown by electron beam induced deposition,” is available through Scientific Reports.
Posted in 3D Printing Technology
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