Tailoring Geometry of Large-Area Hexagonal Close-Packed Plasmonic Nano-Array Structures for Biosensing

Abstract

Generally, a large area of plasmonic nanoarray patterns are employed for biosensing. Electromagnetic (EM) field and Quality-factor (Q-factor, the ratio of the resonance wavelength over its bandwidth) of plasmonic patterns, are important to the sensitivity of plasmon-enhanced biosensors, for example, fluorescence and surface enhanced Rama spectroscopy (SERS) biosensors. Hexagonal close-packed plasmonic nanostructures arranged in nano-disk, nano-ring, nano-disk/ring patterns are prevailing configurations using batch processes (e.g., anodic aluminum oxide (AAO)). Different patterns due to size/geometry difference can have different Q-factors. However, the geometry effect on Q-factor in such configurations is not clear. Therefore, we adopted Finite-difference time-domain (FDTD) simulation to numerically study how EM field and Q-factor are modulated by geometric design of large-area hexagonal close-packed gold disk/ring structures. The simulation results provide guidelines to increase Q-factor to improve the sensitivity of plasmon-enhanced biosensors.