Design of hexagonal gold nano disks for surface-enhanced Raman scattering based sensing

Abstract

Surface-enhanced Raman scattering (SERS), a powerful surface-sensitive analytical technique capable of amplifying weak Raman signals finds application for a wide variety of problems requiring sensitive and targeted analyte detection. To further expand its practical applications, immense research works are going on in the field of designing highly sensitive SERS substrates with the intention of enhancing the signal intensity and improving the detection limit. In this work, we have theoretically designed a three-dimensional SERS substrate based on Au hexagonal nanodisks capable of potential trace detection of chemical, and biological, analytes to the single molecule level. The structure design and the performance evaluations were carried out using the finite element method (FEM) in the visible to near-IR region. Hexagonal nanostructures seem extremely promising in improving Raman detection sensitivity due to the presence of a large number of spatially localized hotspots. Although the SERS effect is primarily focused on surface plasmon resonance from metal nanostructures, the gap between disks significantly contributes to the field enhancement as observed in the monomer, dimer, and trimer hexagonal systems. Various spatially oriented two-dimensional arrays of trimer nanostructures were compared in this study on account of EF to propose a highly efficient SERS sensing platform, enabling the trace detection of chemical, and biological analytes and to the single molecule level applications.