Refractive index sensing and surface-enhanced Raman spectroscopy using silver-gold layered bimetallic plasmonic crystals

Somi Kang, Sean E. Lehman, Matthew V. Schulmerich, An Phong Le, Tae woo Lee, Stephen K. Gray, Rohit Bhargava, Ralph G. Nuzzo

Research output: Contribution to journalArticlepeer-review


Herein we describe the fabrication and characterization of Ag and Au bimetallic plasmonic crystals as a system that exhibits improved capabilities for quantitative, bulk refractive index (RI) sensing and surface-enhanced Raman spectroscopy (SERS) as compared to monometallic plasmonic crystals of similar form. The sensing optics, which are bimetallic plasmonic crystals consisting of sequential nanoscale layers of Ag coated by Au, are chemically stable and useful for quantitative, multispectral, refractive index and spectroscopic chemical sensing. Compared to previously reported homometallic devices, the results presented herein illustrate improvements in performance that stem from the distinctive plasmonic features and strong localized electric fields produced by the Ag and Au layers, which are optimized in terms of metal thickness and geometric features. Finite-difference time-domain (FDTD) simulations theoretically verify the nature of the multimode plasmonic resonances generated by the devices and allow for a better understanding of the enhancements in multispectral refractive index and SERS-based sensing. Taken together, these results demonstrate a robust and potentially useful new platform for chemical/spectroscopic sensing.

Original languageEnglish (US)
Pages (from-to)2492-2503
Number of pages12
JournalBeilstein Journal of Nanotechnology
Issue number1
StatePublished - 2017


  • Finite-difference time-domain
  • Nanoimprint soft lithography
  • Plasmonics
  • Surface plasmon resonance

ASJC Scopus subject areas

  • Materials Science(all)
  • Physics and Astronomy(all)
  • Electrical and Electronic Engineering


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