Numerical investigation of plasmonic bowtie nanorings with embedded nanoantennas for achieving high SEIRA enhancement factors

Abstract

This paper presents the numerical investigation of several complex plasmonic nanostructures — bowtie nanoring and crossed-bowtie nanoring nanoantennas with embedded bowtie nanoantennas and crossed-bowtie nanoantennas — for surface enhanced infrared absorption (SEIRA) spectroscopy-based substrates. The proposed nanostructures exhibit substantially large SEIRA enhancement-factor (~ 8.1 × 105) compared to previously reported enhancement factor values for bowtie nanoantennas or nanoring antennas. The plasmonic properties of the proposed nanostructures have been studied by the numerical evaluation of the near-field electromagnetic enhancement at resonant plasmon mode excitation wavelengths in the mid-IR spectral regime. The highest SEIRA enhancement of ~ 8.1 × 105 occurs at a wavelength of ~ 6800 nm (6.8 μm). A substantial electric field enhancement as large as ~ 375, corresponding to SEIRA EF of ~ 1.4 × 105 is noted even when the minimum gaps between the plasmonic nanostructures is as large as 10 nm, which can easily be fabricated using the conventional nanolithography techniques. The occurrence of several electric field hotspots due to the presence of plasmonic nanoantennas embedded inside the nanorings was observed, as the electric fields are enhanced in the vicinity of the plasmonic nanostructures being proposed. The multiple electric field hotspots in the proposed nanostructures can lead to larger average electric field enhancement as well as the average SEIRA enhancement for these substrates. Moreover, by embedding plasmonic nanoantenna structures inside the bowtie nanorings and crossed-bowtie nanorings, large spectral tunability of plasmon resonance wavelengths is achieved in the spectral regime from 4 μm to 8 μm. This is done by varying a larger number of spectral parameters that are present in these complex nanostructures. This paper also reports a novel configuration of crossed-bowtie nanoring plasmonic structure exhibiting less polarization dependence of the SEIRA enhancement-factor. The proposed structures in this paper can be fabricated by the state-of-the-art nanofabrication technologies.

Surface plasmon resonance effects of silver nanoparticles in graphene-based dye-sensitized solar cells

“…LSPR enhancement is affected by many factors, such as particle size, particle shape, incident light wavelength, dielectric constant of materials, and surface state of particles (Hu et al, 2022;Kim and Ha, 2022;Zhu et al, 2022;Zhu and Zhao, 2022). The LSPR of metal nanoparticles is recognized as an effective approach to improve the performance of photoelectric devices due to its important advantages (Ninawe and Dhawan, 2022;Rasheed and Sayidmarie, 2022).…”