Stamping plasmonic nanoarrays on SERS-supporting platforms

Abstract

The dielectric property of a nanoparticle-supporting film has recently garnered attention in the fabrication of plasmonic surfaces. A few studies have shown that the localized surface plasmon resonance (LSPR), and hence surface-enhanced Raman scattering (SERS), strongly depends on the substrate refractive index. In order to create higher efficiency SERS-active surfaces, it is therefore necessary to consider the substrate property along with nanoparticle morphology. However, due to certain limitations of conventional lithography, it is often not feasible to create well-defined plasmonic nanoarrays on a substrate of interest. Here, an additive nanofabrication technique, i.e., nanotransfer printing (nTP), is implemented to integrate electron beam lithography (EBL) defined high-aspect-ratio nanofeatures on a variety of SERS-supporting surfaces. With the aid of suitable surface chemistries, a wide range of plasmonic particles were successfully integrated on surfaces of three physically and chemically distinct dielectric materials, namely, polydimethyl siloxane (PDMS), SU-8 photoresist, and glass surfaces, using silicon-based relief pillars. These nTP-created metal nanoparticles strongly amplify the Raman signal and complement the selection of suitable substrates for better SERS enhancement. Our experimental observations are also supported by theoretical calculations. The implementation of nTP to stamp out metal nanoparticles on a multitude conventional/unconventional substrates has novel applications in designing in-built plasmonic microanalytical devices for SERS sensing and other related photonic studies. Copyright © 2011 John Wiley & Sons, Ltd.