Understanding the effects of dielectric medium, substrate, and depth on electric fields and SERS of quasi-3D plasmonic nanostructures

Abstract

The local electric field distribution and the effect of surface-enhanced Raman spectroscopy (SERS) were investigated on the quasi-3D (Q3D) plasmonic nanostructures formed by gold nanohole and nanodisc array layers physically separated by a dielectric medium. The local electric fields at the top gold nanoholes and bottom gold nanodiscs as a function of the dielectric medium, substrate, and depth of Q3D plasmonic nanostructures upon the irradiation of a 785 nm laser were calculated using the three-dimensional finite-difference time-domain (3D-FDTD) method. The intensity of the maximum local electric fields was shown to oscillate with the depth and the stronger local electric fields occurring at the top or bottom gold layer strongly depend on the dielectric medium, substrate, and depth of the nanostructure. This phenomenon was determined to be related to the Fabry-Pérot interference effect and the interaction of localized surface plasmons (LSPs). The enhancement factors (EFs) of SERS obtained from the 3D-FDTD simulations were compared to those calculated from the SERS experiments conducted on the Q3D plasmonic nanostructures fabricated on silicon and ITO coated glass substrates with different depths. The same trend was obtained from both methods. The capabilities of tuning not only the intensity but also the location of the maximum local electric fields by varying the depth, dielectric medium, and substrate make Q3D plasmonic nanostructures well suited for highly sensitive and reproducible SERS detection and analysis.

3D Cross‐Point Plasmonic Nanoarchitectures Containing Dense and Regular Hot Spots for Surface‐Enhanced Raman Spectroscopy Analysis

“…The maximum field enhancement is similar for 8 and 10 layers of stacking. The irregular e‐field enhancement can be attributed to the interference of waves propagating back and forth across the stacking layers . The interference might be constructive or destructive, which affects the local field enhancement across the 3D network.…”

Laser-induced damage properties of antireflective porous glasses

“…Therefore, the simulation model is designed for singleside etched substrates. The models were conducted using a single hole as the unit cell, with the periodic boundary conditions applied to the x-and y-directions to describe an infinite square array and uniaxial perfectly matched layers along the z-direction [14]. The source of the input plane wave pulse was placed 70 nm above the top of nanoholes and polarized to the x-axis.…”

Investigation of a quasi-3D plasmonic nanostructure for TE and TM polarizations

“…Recently these structures have attracted much attention [12][13][14][15][16][17][18][19][20][21]. They have been used as EOT structures, where, at special frequencies, they have shown larger transmission than nanohole arrays alone [14,19].…”

“…They have been used as EOT structures, where, at special frequencies, they have shown larger transmission than nanohole arrays alone [14,19]. Q3D plasmonic nanostructures have also been used in SERS applications for achieving higher Raman signals [13,[15][16][17][18]. They have also been investigated as refractive index sensors [12,21].…”