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The influence of the fabrication developing time on plasmonic bowtie nanoantenna metastructures
Author(s): Caroline Campbell; Abigail Casey; Dhruv Fomra; Justine Drobitch; Gregory Triplett
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Paper Abstract

Plasmonic bowtie nanoantennas, which are metastructures that manipulate light and generate an intense localized electric field, demonstrate potential for surface enhanced Raman spectroscopy (SERS) signaling. Nanoantenna-based SERS can be employed to amplify molecular fingerprints, which is important for biomolecular and chemical reaction sensing. Nanoantenna electric field (or hot spot) optimization occurs when the plasmonic resonant wavelength of the structure closely matches the wavelength of the incident light. Depending on the excitation wavelength, the fabrication procedures can have tighter constraints. In this work, we fabricated several device arrays following nanoantenna design optimization for operation at 532nm wavelength. Fabrication steps utilized electron beam lithography (EBL) and nanopatterning tools, development, physical vapor deposition (PVD) by electron beam evaporation deposition (EBED), and resist removal by lift off. The polymer resist employed consist of a bilayer of polymethyl methacrylate (PMMA) in anisole (495k M.W. and 950k M.W.) sourced from MicroChem, Corp. The developer used (also sourced from MicroChem, Corp) was methyl isobutyl ketone: isopropyl alcohol (MIBK:IPA) in a 1:3 ratio. The influence of the developer step on the shape and quality of nanoantenna arrays was studied as the bowtie nanoantennas merged together or lost their defined shape. This study explored a specific bowtie nanoantenna design of 90-nm side lengths and 50-nm gap size, and 532-nm by 1.5 μm separation from its nearest neighbor. These nanoantennas were patterned in 10x5 and 10x25 grids with varying developer exposure times (10-100 seconds). Results reveal that the final device footprint has clear and defined shapes at as well as merged, undefined shapes across at 10-second window (40s-50s). At the upper end of the window, a greater than 40% increase in nanoantenna surface area is consistently observed.

Paper Details

Date Published: 9 September 2019
PDF: 7 pages
Proc. SPIE 11082, Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVII, 110822I (9 September 2019); doi: 10.1117/12.2529674
Show Author Affiliations
Caroline Campbell, Virginia Commonwealth Univ. (United States)
Abigail Casey, Virginia Commonwealth Univ. (United States)
Dhruv Fomra, Virginia Commonwealth Univ. (United States)
Justine Drobitch, Virginia Commonwealth Univ. (United States)
Gregory Triplett, Virginia Commonwealth Univ. (United States)


Published in SPIE Proceedings Vol. 11082:
Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVII
Din Ping Tsai; Takuo Tanaka, Editor(s)

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