Guided-Mode Resonance Grating with Self-Assembled Silver Nanoparticles for Surface-Enhanced Raman Scattering...

Area of Science:

• Nanophotonics
• Spectroscopy
• Materials Science

Background:

• Surface-enhanced Raman scattering (SERS) requires nanostructures to enhance electromagnetic fields.
• Indium-tin-oxide (ITO) is a transparent conductive oxide with a high refractive index.
• Guided-mode resonance (GMR) gratings can create strong localized electromagnetic fields.

Purpose of the Study:

• To design and fabricate GMR gratings on ITO thin films.
• To utilize these gratings for enhanced SERS spectroscopy.
• To investigate the performance of silver nanoparticle-decorated ITO gratings for SERS sensing.

Main Methods:

• Fabrication of GMR gratings on ITO thin films.
• Self-assembly of silver nanoparticles (NPs) onto the grating surface.
• SERS measurements using 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) as a probe molecule.
• Analysis of enhancement factor and limit of detection (LOD).

Main Results:

• ITO gratings provided a significantly enhanced local electric field for SERS.
• Silver NPs on ITO gratings generated numerous "hot-spots" for SERS sensing.
• The fabricated ITO gratings showed excellent tolerance to fabrication deviations.
• An enhancement factor of approximately 14× was achieved for DTNB on ITO gratings compared to a flat ITO film.
• A limit of detection (LOD) as low as 10 pM for DTNB was demonstrated.

Conclusions:

• ITO-based GMR gratings are effective platforms for SERS applications.
• The combination of GMR and silver NPs offers a promising approach for highly sensitive SERS detection.
• The developed method exhibits robustness and high sensitivity, suitable for various sensing applications.