Partially embedded gold nanoislands in a glass substrate for SERS applications

Abstract

We investigate the surface enhanced Raman scattering (SERS) of biomolecules attached to partially embedded gold nanoislands in a transparent substrate. In order to generate SERS hot spots in a large area, partially-embedded gold nanoislands were fabricated via thermal annealing of a thin gold layer. The partially embedded gold nanoislands have average sizes varying from 10 nm to 50 nm. The SERS performance has been investigated for samples made with various thicknesses of gold thin film. The SERS spectra showed that a gold thin film with 4.5 nm initial thickness can produce the highest SERS signal due to the high density of uniform partially embedded gold nanoislands with average size around 22 nm. Furthermore, we perform numerical simulations based on rigorous coupled-wave analysis (RCWA) and finite difference time domain (FDTD) to show that the SERS enhancement originates from enhanced electric fields surrounding the partially embedded gold nanoislands. Hence, we have demonstrated a simple, stable, large-area, and low cost preparation process for producing a SERS platform with excellent sensitivity for biosensing.