Nanocap array of Au:Ag composite for surface-enhanced Raman scattering

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) requires optimized nanostructured substrates for high sensitivity.
• Bimetallic nanostructures offer tunable plasmonic properties for enhanced SERS performance.

Purpose of the Study:

• To fabricate and characterize a novel Au:Ag bimetallic nanocap array SERS substrate.
• To investigate the influence of co-sputtering and nanogap engineering on SERS enhancement.
• To evaluate the sensitivity and reproducibility of the developed SERS substrate.

Main Methods:

• Fabrication of Au:Ag nanocap arrays using co-sputtering onto polystyrene colloidal sphere templates.
• Utilizing magnetron sputtering for controlled deposition of gold and silver nanoparticles.
• Employing O2-plasma etching to engineer nanogaps for enhanced surface plasmon resonance (SPR).
• Characterization of SERS performance using Rhodamine 6G as a probe molecule.

Main Results:

• Co-sputtered Au:Ag arrays formed a waxberry-like structure with enhanced Raman signal compared to bilayer arrays.
• The Au:Ag bimetallic arrays showed a 4-fold increase in SERS signal intensity for Rhodamine 6G.
• Optimized nanogaps in Au:Ag nanocaps led to even stronger SERS enhancements due to plasmon coupling.
• Achieved an enhancement factor (EF) of 6.72×10^10 for Rhodamine 6G detection.

Conclusions:

• The developed Au:Ag nanocap array SERS substrate exhibits high sensitivity and reproducibility.
• Co-sputtering and nanogap engineering are effective strategies for enhancing SERS performance.
• This novel SERS substrate holds promise for sensitive molecular detection applications.