FDTD Analysis on Geometrical Parameters of Bimetallic Localized Surface Plasmon Resonance-Based Sensor

The localized surface plasmon resonance (LSPR) properties are numerically analyzed using finite-difference time domain (FDTD) method, which is a reliable technique in solving Maxwell's equations in dispersive medium. Optical properties and LSPR characteristics were analyzed with Titanium Nitride (TiN) as an adhesion layer at gold(Au)/silver(Ag) interface. The reflection spectra of bimetallic layer nano-holes was compared with various metallic layer thicknesses of Au and Ag, hole radii and lattice period. When compared between single and bimetallic Ag/TiN/Au nano-hole layers, it showed that the layer with 70nm-thick Ag/5nm-thick TiN/50nm-thick Au (Ag70/TiN5/Au50) gave greater LSPR-based sensor performance with narrower plasmonic line width and better full width at half maximum (FWHM). Change in geometrical parameters such as lattice period and hole radii was affected the sensitivity and detection accuracy of Ag70/TiN5/Au50 nano-hole layer; which maximum of 90.9% reflection intensity and minimum of 18nm FWHM were obtained.