title: High Aspect-Ratio Iridium-Coated Nanopillars for Highly Reproducible Surface-Enhanced Raman Scattering (SERS).
abstract: A variety of different gold and silver nanostructures have been proposed over the years as high sensitivity surface-enhanced Raman scattering (SERS) sensors. However, efficient use of SERS has been hindered by the difficulty of realizing SERS substrates that provide reproducible SERS response over the whole active area. Here, we show that atomic layer deposition (ALD) grown iridium can be used to produce highly reliable SERS substrates. The substrates are based on a periodic array of high aspect-ratio iridium coated nanopillars that feature efficient and symmetrically distributed hot spots within the interpillar gaps (gap width<10 nm). We show that the enhancement with the iridium based nanostructures is of significant magnitude and it equals the enhancement of silver based reference substrates. Most notably, we demonstrate that the ordered and well-defined plasmonic nanopillars offer a measurement-to-measurement variability of 5%, which paves the way for truly quantitative SERS measurements.
authors.affiliation: †School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.|‡Institute of Photonics, University of Eastern Finland (Joensuu Campus), P.O. Box 111, FI-80101Joensuu, Finland.
authors.forename: Guoguo
authors.initials: G
authors.lastname: Kang
authors.affiliation: ‡Institute of Photonics, University of Eastern Finland (Joensuu Campus), P.O. Box 111, FI-80101Joensuu, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Matikainen
authors.affiliation: ‡Institute of Photonics, University of Eastern Finland (Joensuu Campus), P.O. Box 111, FI-80101Joensuu, Finland.
authors.forename: Petri
authors.initials: P
authors.lastname: Stenberg
authors.affiliation: §Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Färm
authors.affiliation: †School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.affiliation: §Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Ritala
authors.affiliation: ‡Institute of Photonics, University of Eastern Finland (Joensuu Campus), P.O. Box 111, FI-80101Joensuu, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Vahimaa
authors.affiliation: ‡Institute of Photonics, University of Eastern Finland (Joensuu Campus), P.O. Box 111, FI-80101Joensuu, Finland.
authors.forename: Seppo
authors.initials: S
authors.lastname: Honkanen
authors.affiliation: †School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Xiaodi
authors.initials: X
authors.lastname: Tan
keywords: atomic layer deposition (ALD); biosensor; iridium; localized surface plasmons (LSPs); nanogap; plasmonic nanopillars; surface-enhanced Raman scattering (SERS)