Surface-Enhanced Raman Scattering (SERS) Studies of Disc-on-Pillar (DOP) Arrays: Contrasting Enhancement Factor with...

Area of Science:

• Nanotechnology
• Plasmonics
• Analytical Chemistry

Background:

• Nanomachining enables reproducible nano-arrayed devices, revolutionizing plasmonic sensing.
• Tailored interparticle gaps in plasmonic platforms enhance performance for surface-enhanced Raman scattering (SERS).
• A challenge exists in balancing substrate sensitivity for quantitative SERS analysis with optimized electromagnetic field enhancement.

Purpose of the Study:

• To assess the enhancement factor and analytical performance of plasmonic silver/silicon disc-on-pillar (DOP) arrays with variable pitch for quantitative applications.
• To compare experimental data with finite-difference time-domain (FDTD) simulations for optimizing array dimensions.

Main Methods:

• Fabrication of plasmonic Ag/SiO2/Si DOP arrays with varying pitches.
• Characterization of SERS substrate enhancement factor (SSEF) using benzenethiol self-assembled monolayers.
• Quantitative analysis of analytes like rhodamine 6G (R6G) and 4-aminobenzoic acid.
• Comparison of experimental results with FDTD simulations.

Main Results:

• Highly reproducible SERS signals (RSD ~4-10%) and SSEF values of 10^6-10^8 were achieved across all pitches.
• Densely packed DOP arrays (160 nm pitch, 40 nm gap) demonstrated superior analytical performance for quantitation.
• The highest SSEF was observed for wider-spaced arrays (520 nm pitch, 400 nm gap).

Conclusions:

• Plasmonic Ag/SiO2/Si DOP arrays are effective SERS substrates with high reproducibility and enhancement factors.
• Optimized interparticle spacing is crucial for achieving quantitative SERS analysis, with denser arrays favoring quantitation.
• FDTD simulations are valuable tools for optimizing plasmonic array dimensions for SERS applications.