Fabrication and analysis of concentric gold nanoring arrays with sub-10 nm gap for Surface-Enhanced Raman Scattering effect

Abstract

Surface-Enhanced Raman Scattering (SERS) has been widely used to characterize molecular structure and detect single molecule. Several metal nanostructures such as nano-hole, nanogap have been proposed to maximize plasmonic properties and sensitivity. The most important issue for real SERS application is fabrication of sub-10 nm nanogap with well-defined and large-area uniformity. To develop more efficient sensor, designing of near-field localization properties of plasmonic nanostructures is another key factor. In this thesis, we introduce a reproducible and highly-throughput method to make sub-10 nm gap array with ultra-high density and precise gap size control by combining colloidal lithography and directed self-assembly of block copolymers (BCPs). With this method, we fabricated near-field focusing concentric geometric nanoring pattern with sub-10 nm plasmonic gaps. In addition, by controlling the total molecular weight of block copolymers (BCPs) and nano-sphere diameter, the gap distance and near-field focusing properties are maximized. Sur-face-enhanced Raman scattering (SERS) measurements show that concentric nanofocusing structure with sub-10 nm gap arrays has advantage for practical applications.