Periodic Arrays of Plasmonic Ag-Coated Multiscale 3D-Structures with SERS Activity: Fabrication, Modelling and Characterisation

Marta Lafuente*, Lucas J. Kooijman, Sergio G. Rodrigo, Erwin Berenschot, Reyes Mallada, María P. Pina, Niels R. Tas, Roald M. Tiggelaar*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Surface enhanced Raman spectroscopy (SERS) is gaining importance as sensing tool. However, wide application of the SERS technique suffers mainly from limitations in terms of uniformity of the plasmonics structures and sensitivity for low concentrations of target analytes. In this work, we present SERS specimens based on periodic arrays of 3D-structures coated with silver, fabricated by silicon top-down micro and nanofabrication (10 mm × 10 mm footprint). Each 3D-structure is essentially an octahedron on top of a pyramid. The width of the top part—the octahedron—was varied from 0.7 µm to 5 µm. The smallest structures reached an analytical enhancement factor (AEF) of 3.9 × 107 with a relative standard deviation (RSD) below 20%. According to finite-difference time-domain (FDTD) simulations, the origin of this signal amplification lies in the strong localization of electromagnetic fields at the edges and surfaces of the octahedrons. Finally, the sensitivity of these SERS specimens was evaluated under close-to-reality conditions using a portable Raman spectrophotometer and monitoring of the three vibrational bands of 4-nitrobenzenethiol (4-NBT). Thus, this contribution deals with fabrication, characterization and simulation of multiscale 3D-structures with SERS activity.

Original languageEnglish
Article number1129
JournalMicromachines
Volume15
Issue number9
DOIs
Publication statusPublished - Sept 2024

Keywords

  • FDTD simulations
  • Multiscale dimensions
  • Periodic arrays
  • Pyramids and octahedrons
  • SERS activity
  • Silicon micromachining
  • Silver-coated 3D-structures

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