Two-dimensional, periodic mushroomlike nanostructures for SERS applications

Abstract

Two-dimensional, large-area, periodic mushroomlike metallodielectric nanostructures have been simulated, fabricated, and characterized for biosensing applications. Simulations show high electrical field around the tips of the structure. The fabrication process consists of using holographic lithography to create 2-D periodic nanohole array. Subsequently, oblique metal deposition on the nanohole array results in mushroomlike nanostructure with a cavity underneath the void space. The precise geometry of the nanocavity is dependent on the deposition time (thickness). The periodicity of the array was designed to excite propagating surface plasmon resonance (SPR) modes, while the geometric shape of the nanostructure excites localized plasmons on its edges. The coupling between these two phenomena results in higher electric field and thus higher enhancement factor than conventional nanohole array over the whole substrate area ( g 4 cm2). By analyzing the Raman mode of the adsorbed benzenethiol on the surface, the surface enhanced Raman scattering (SERS) enhancement factor of greater than 106 has been measured. Due to its moderately-high enhancement factor, large-area array, and low-cost fabrication method, this nanostructure can be used for future SERS biosensing applications.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.