Large-Area Plasmon Mapping via an Optical Technique: Silver Nanohole Array and Nano-Sawtooth Structures

Abstract

Silver nanostructures are among the most important platforms for developing efficient plasmonic materials, and edges and/or spikes in such structures can produce highly localized surface plasmons, resulting in dramatic electromagnetic field enhancement. In addition, if the enhanced field and/or localized surface plasmons were to be visualized in a periodic structure with long-range order, then this data would be invaluable for plasmonics researchers and engineers. Herein, we present an optical technique for plasmon mapping in the silver nanohole array and edge (nano-sawtooth) structures over large areas (∼10 μm). Plasmon mapping via two-dimensional fluorescence intensity enhancement quantification with submicrometer spatial resolution revealed high enhancement factors of up to 200 for the nano-sawtooth structure. These measurements were performed alongside atomic force microscopy, scanning electron microscopy, and finite-difference time-domain calculations, and the enhancement mechanism was investigated. Furthermore, the silver nanohole array and nano-sawtooth structures were fabricated using straightforward and cost-effective processes.

1D, 2D, and 3D Mapping of Plasmon and Mie Resonances: A Review of Field Enhancement Imaging Based on Electron or Photon Spectromicroscopy

“…In the second representative study, plasmon mapping over a large area (∼10 μm) at a height of a few hundred nanometers was achieved. The Saitow group demonstrated plasmon mapping of the periodic structure in a Ag 2D nanohole array sample via fluorescence intensity enhancement using not SNOM but confocal (i.e., far-field) spectromicroscopy . The highest enhancement factor (∼200) was observed at the edge of the periodic nanostructure, corresponding to a Ag nanosawtooth.…”

“…Ag nanohole and nanosawtooth structures imaged using (a) SEM and (b) optical microscopy; (c) plasmon map of the same structure; (d) overlaid images. Reproduced with permission from ref . Copyright 2023 American Chemical Society.…”

“…Although the studies discussed above have yielded many excellent results, in general, there is a lack of literature on Mie resonances. In fact, the author surveyed many papers on surface plasmon resonances investigated by CL, EELS, and SNOM (150 papers, including refs − …”

“…In contrast, localized surface plasmon imaging can be extended to the observation of long-range periodic order (ca. 10–100 μm) using far-field confocal spectromicroscopy . This technique has been applied to create 1D, 2D, and 3D maps of the Mie scattering/resonance of submicron-sized semiconductor , and 2D transition metal dichalcogenide (2D TMD) , materials, revealing both electric and magnetic field enhancements in the visible-to-near-IR region.…”

Transmission enhancement in coupled nanohole and nanodisk arrays for solar blind UV filter

“…Furthermore, aluminum is favored in existing CMOS processes, making it the most suitable candidate for UV applications. Two-dimensional (2D) nanohole arrays [22][23][24][25][26][27] have been used in various fields and bands. Al nanohole arrays have been designed to operate as bandpass filters in the 200-400 nm waveband, and EOT on these simple metallic nanohole arrays has been achieved from 10% to 30% based on the mechanism of surface plasmon resonance (SPR).…”