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[Illinois] Advanced Materials Characterization Workshop 2012: Nanofabrication of Plasmonic Devices in the Helium Ion Microscope

By Larry Scipioni

Carl Ziess Microscopy

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Helium ion microscopy (HIM) is being used both to create and to inspect nanostructures for photonic and plasmonic devices. As part of a program exploring photoelectrons as sources for multiple beam electron beam lithography, fractal apertures are being developed to generate a sub-20nm light source using surface plasmon resonance. The fabrication was carried out by direct write helium ion milling into a 90 nm thick aluminum film deposited by evaporation onto a fused silica substrate. A machining precision of 5 nm was obtained, allowing the creation of sharp, vertical edges and corners with the required radius of curvature. These results are compared to previous attempts to achieve these geometries with electron beam lithography and Ga FIB milling.

In order to complete the photoemitter, the surface of the Al film was subsequently coated with a CsBr thin-film (10 nm) photocathode. The ‘C’ shape of the aperture concentrates the light energy directly over the tongue, where the metal film is re-entrant into the aperture. This dimension is approximately 20 nm, far below the ordinary diffraction limit. The average photocurrent measured from the apertures is approximately 260 pA. Considering the 22 nm2 source size as calculated by Finite Difference Time Domain simulations, the current density appears to surpass that of thermionic electron emitters.


Larry Scipioni is the Director of Applications Research for Carl Zeiss SMT, Inc

Sponsored by



Engineering Sciences Building, University of Illinois at Urbana-Champaign, Urbana, IL


NanoBio Node, Charlie Newman, Obaid Sarvana, AbderRahman N Sobh

University of Illinois at Urbana-Champaign

Tags, a resource for nanoscience and nanotechnology, is supported by the National Science Foundation and other funding agencies. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.