Fabrication of bow-tie antennas with mechanically tunable gap sizes below 5 nm for single-molecule emission and Raman scattering

Cynthia M. Gruber, Lars O. Herrmann, Antonis Olziersky, Gabriel F. Puebla-Hellmann, Ute Drechsler, Tobias von Arx, Michael Bachmann, Michael Koch, Zachary J. Lapin, Koushik Venkatesan, Lukas Novotny, Emanuel Lörtscher

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

7 Citations (Scopus)


Raman spectroscopy is a powerful tool to unambiguously identify chemical compounds by their unique vibrational finger-print. The Raman cross-section of a single molecule, however, is extremely small and intense laser sources, long integration times and high concentrations of analytes are typical prerequisites for Raman spectroscopy. A common route to alleviate these drawbacks is the use of surface plasmon polaritons (SPP) to guide and concentrate light in constrained geometries such as nanometer-sized gaps. The resulting local electric field and chemical enhancements are sufficient to perform surface-enhanced Raman spectroscopy (SERS) down to the single-molecule level. Here, we demonstrate advances in nanolithography which enable reproducible fabrication of optical antennas for the visible range with sub-5 nm features on large and wavy substrates. A material-independent process route is described that employs cutting-edge electron-beam lithography (EBL) operated in ultra-silent laboratories to enable undisturbed lithography. Through the use of a reactive ion etching step, free-standing antennas with pillar heights of up to 250 nm have been fabricated. These antennas show a three-fold increase in luminescence intensity and spatial confinement in comparison to antennas in direct contact with the substrate. This underlines their great potential for optical direct-sensing experiments targeting few to single molecules in the feed-gap region through SERS.

Original languageEnglish
Title of host publication2015 IEEE 15th International Conference on Nanotechnology
Subtitle of host publicationIEEE-NANO 2015
Place of PublicationPiscataway, NJ
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages5
ISBN (Electronic)9781467381550
ISBN (Print)9781467381574
Publication statusPublished - 2015
Externally publishedYes
Event15th IEEE International Conference on Nanotechnology, IEEE-NANO 2015 - Rome, Italy
Duration: 27 Jul 201530 Jul 2015


Other15th IEEE International Conference on Nanotechnology, IEEE-NANO 2015


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