Spaced Hybrid TiO₂/Au Nanotube Arrays with Tailored Optical Properties for Surface-Enhanced Raman Scattering

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Controlling plasmonic material geometry is key to tailoring optical responses for device enhancement.
• Gold (Au) nanoparticles on titanium dioxide (TiO2) offer tunable plasmonic properties.

Purpose of the Study:

• To demonstrate a simple method for controlling Au nanoparticle size and distribution on TiO2 nanotubes.
• To investigate the impact of controlled nanoparticle geometry on optical properties and SERS performance.

Main Methods:

• Utilized magnetron sputtering to deposit Au nanoparticles onto spaced TiO2 nanotubes.
• Varied deposition time to control Au nanoparticle size, distribution, and effective thickness.
• Analyzed optical absorption spectra and surface-enhanced Raman scattering (SERS) signals.

Main Results:

• Shorter sputtering times yielded small, well-separated Au nanoparticles.
• Longer sputtering times resulted in quasi-continuous Au layers with small interparticle gaps.
• Optical absorption showed strong peaks (200-550 nm) and decreasing absorption with increasing Au thickness (550-1100 nm).
• Enhanced SERS signal amplification and improved detection limits were observed with quasi-continuous Au layers.

Conclusions:

• Sputtering time is an effective parameter for controlling Au nanoparticle morphology on TiO2 nanotubes.
• Tailored nanoparticle geometry influences optical absorption and SERS enhancement.
• The developed method enables the design of efficient plasmonic devices for applications in optical sensing and detection.