Strongly coupled, high-quality plasmonic dimer antennas fabricated using a sketch-and-peel technique

M. Gittinger1, K. Höflich2,3, V. Smirnov1, H. Kollmann1, C. Lienau1 and M. Silies1

Published in:

Nanophotonics, vol. 9, no. 2, pp. 401-412, doi:10.1515/nanoph-2019-0379 (2020).

Open Access. © 2019 Christoph Lienau, Martin Silies et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 Public License.

Abstract:

A combination of helium- and gallium-ion beam milling together with a fast and reliable sketch-and-peel technique is used to fabricate gold nanorod dimer antennas with an excellent quality factor and with gap distances of less than 6 nm. The high fabrication quality of the sketch-and-peel technique compared to a conventional ion beam milling technique is proven by polarisation-resolved linear dark-field spectromicroscopy of isolated dimer antennas. We demonstrate a strong coupling of the two antenna arms for both fabrication techniques, with a quality factor of more than 14, close to the theoretical limit, for the sketch-and-peel-produced antennas compared to only 6 for the conventional fabrication process. The obtained results on the strong coupling of the plasmonic dimer antennas are supported by finite-difference time-domain simulations of the light-dimer antenna interaction. The presented fabrication technique enables the rapid fabrication of large-scale plasmonic or dielectric nanostructures arrays and metasurfaces with single-digit nanometer scale milling accuracy.

1 Institute of Physics and Center of Interface Science, Carl von Ossietzky Universität Oldenburg, D-26129 Oldenburg, Germany
2 Helmholtz Zentrum für Materialien und Energie Berlin, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
3 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany

Keywords:

helium-ion beam lithography; sketch and peel; plasmonic nanostructures; single-particle dark-field