Optical properties and surface-enhanced Raman scattering of quasi-3D gold plasmonic nanostructures

Surface-enhanced Raman scattering (SERS) and optical properties on quasi-3D gold nanohole arrays with precisely controlled size and shape (circle and triangle) were investigated. The nanostructures with circular nanoholes exhibit two to three orders of magnitude higher SERS signals than those with triangular nanoholes. While the enhancement factor (EF) varies with the diameter of nanoholes for circular shaped nanostructures and shows the maximum EF for the nanostructure with 300 nm diameter, the EF for triangular shaped nanostructures does not change with the length of triangles. The normal transmission spectroscopy of white light and the electric field distributions upon the illumination of a 785 nm laser were calculated using the three-dimensional finite-difference time-domain (3D-FDTD) method. The relationship between SERS optical properties such as normal transmission spectra, and electric field distributions was discussed The broad tunable quasi-3D plasmonic nanostructures could have great potential applications in chemical and biological sensors based on SERS platform with molecular identity.