High Aspect Ratio Plasmonic Nanostructures for Sensing Applications

Abstract

We present an experimental and theoretical study of plasmonic modes in high aspect ratio nanostructures in the visible wavelength region and demonstrate their high performance for sensing applications. Ordered and well-defined plasmonic structures with various cross-sectional profiles and heights are obtained using a top-down fabrication process. We show that, compared to cylindrical nanorods, structures with split-ring resonator-like cross sections have great potential for powerful sensing due to a pronounced polarization dependence, strong field enhancement, structural tunability, and improved mechanical stability. The plasmonic structures under study exhibit high sensitivities, up to nearly 600 nm/RIU, and figures of merit above 20.

Magnetic Hot Spots in Closely Spaced Thick Gold Nanorings

“…After development, the resist voids were filled with gold by electroplating, and the remaining PMMA mold was subsequently removed by oxygen plasma etching. The powerful electron beam tool provided precise structuring at the nanoscale, 21 which allowed us to fabricate a wide range of nanoring structures of varying diameter, spacing and height, resulting in various aspect-ratios. In contrast to fabrication based on lift-off, 19 The resonance wavelength of the magnetic LSPR depends on several parameters that permits us to tune the response over the whole NIR range.…”

Dislocated Double-Layered Metal Gratings: Refractive Index Sensors with High Figure of Merit

“…Generally, the standard FOM value of plasmonic sensors is defined as FOM=S (nm RIU −1 )/FWHM (nm) or FOM E =S (eV RIU −1 )/FWHM (eV), where S (nm RIU −1 ) and S (eV RIU −1 ) refer to the sensitivities to the refractive index change in wavelength unit and energy unit, respectively, and FWHM (nm) and FWHM (eV) refer to the linewidths of the plasmonic resonance in wavelength unit and energy unit, respectively. The maximum values of FOM of the LSPR-WA(1) eff mode are determined to be 36 (38) and 32 (31) for the RI ranges of 1.333~1.398 (D2) and 1.398~1.443 (D3) in wavelength (energy) unit, respectively (the detailed sensing data are shown in Table 1), which surpass the values for most of plasmonic sensors, including metal nanoparticle-based sensors and a number of the LSPRrelated sensors using Fano resonance under normal incidence [37,38,[44][45][46][47][48]. DDMG is somewhat similar to the gold mushroom array (GMRA) in two-dimensional structure we reported previously [21].…”

High resolution spin-on electron beam lithography resist with exceptional dry etching resistance

“…The trend of ever decreasing feature sizes in subsequent lithography generations runs parallel to the need for higher performance resists, in terms of resolution, contrast and etch resistance during pattern transfer [2][3][4][5]. In particular, a range of applications, including X-ray Fresnel lenses [6,7], NEMS [8][9][10], photonic metamaterials [11][12][13], polarizers [14][15][16], and biomolecules sorting devices [17,18] require the ability of fabricating high-resolution high-aspect-ratio structures. However, this usually entails a trade-off between the best performing conditions for attaining the highest resolution by electron beam lithography (EBL), i.e.…”