Exploring SERS from complex patterns fabricated by multi-exposure laser interference lithography

Area of Science:

• Plasmonics
• Nanotechnology
• Surface Science

Background:

• Uniform plasmonic surfaces are crucial for reproducible surface-enhanced Raman scattering (SERS) applications.
• Periodic nanostructures offer tunable optical properties and uniform SERS response.
• Laser interference lithography (LIL) is a maskless technique for fabricating periodic patterns.

Purpose of the Study:

• To develop a cost-effective fabrication method for large-area uniform plasmonic surfaces for SERS.
• To explore complex interference patterns using multi-exposure laser interference lithography (MELIL).
• To evaluate the SERS performance and optical properties of MELIL-fabricated patterns.

Main Methods:

• Utilized multi-exposure laser interference lithography (MELIL) to create complex periodic nanostructures.
• Deposited gold (Au) via e-beam evaporation and silver (Ag) via electroplating.
• Performed quantitative Raman scattering measurements and optical simulations.

Main Results:

• Achieved highly uniform SERS with a relative standard deviation below 6% in complex geometries.
• Demonstrated significant Raman enhancement factors of 0.387 × 10^5 (Au) and 1.451 × 10^5 (Ag).
• Optical simulations revealed broadened and shifted absorption peaks, indicating tunable optical properties.

Conclusions:

• MELIL is a versatile and cost-effective method for fabricating uniform plasmonic surfaces for SERS.
• Vacuum-free silver electroplating offers enhanced performance and cost-effectiveness.
• The MELIL process allows for expanded optical tunability, broadening SERS applications.