Lithography-free fabrication of scalable 3D nanopillars as ultrasensitive SERS substrates

Anisha Chirumamilla*, Ioana Malina Moise, Ziru Cai, Fei Ding, Karina B. Jensen, Deyong Wang, Peter K. Kristensen, Lars R. Jensen, Peter Fojan, Vladimir Popok, Manohar Chirumamilla, Kjeld Petersen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Surface-enhanced Raman spectroscopy (SERS) detection of analyte molecules at ultra-low concentrations requires highly-efficient plasmonic nanostructures enabling a high hot-spot density. However, a facile and cost-effective strategy toward large-area fabrication of efficient nanostructures with significant electromagnetic field enhancement remains a great challenge. Further, SERS faces reliability issues with the molecular fingerprint at ultra-low concentrations. This work shows a one-step rapid fabrication technique utilizing glancing angle deposition for growing 3D nanopillars of Ag or Au, which is facile, scalable and cost-effective. The 3D nanopillar substrates can reliably detect analyte molecules with concentrations as low as 10-18 M with a high signal-to-noise ratio molecular fingerprint proven for Cresyl violet, p-aminothiophenol and Rhodamine 6G. The ultra-high enhancement is realized in conjunction with the formation of a high hot-spot density due to localized surface plasmons and surface plasmons at metal/air interface. A portable handheld Raman spectrometer is used to evaluate the potential application of the nanopillars for on-site diagnostics. It avoids the need for sophisticated tabletop instruments yet provides high-precision molecular specificity outside specialized laboratories. The 3D nanopillar substrates show excellent molecular detection limits at 10−15 M concentrations when tested with a handheld Raman spectrometer. The uniqueness of the 3D nanopillar features with the formation of a high density of hot-spots and one-step nanofabrication methods provide a platform to unravel on-site diagnostics with cost-effective approaches.

Original languageEnglish
Article number101763
JournalApplied Materials Today
Volume31
Number of pages10
ISSN2352-9407
DOIs
Publication statusPublished - Apr 2023

Keywords

  • 3D nanopillars
  • Gap plasmon resonator
  • Large-area plasmonic substrates
  • One-step nanofabrication
  • Surface-enhanced Raman spectroscopy

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