Silver nanowires with optimized silica coating as versatile plasmonic resonators

Area of Science:

• Plasmonics and Nanophotonics
• Materials Science and Engineering

Background:

• Metal nanoparticles are common in plasmonics, but metal nanowires offer advantages like larger interaction volume and higher quality factors.
• Precise control over the distance between nanowires and substrates or other materials is essential for integrated plasmonic circuits.
• Dielectric coatings can control this distance but must not compromise plasmonic properties.

Purpose of the Study:

• To introduce a controlled synthesis and coating approach for silver nanowires (AgNWs).
• To achieve sub-nanometer precision in controlling the distance of AgNWs for integrated hybrid dielectric-plasmonic circuits.
• To ensure dielectric coatings do not degrade the plasmonic properties of AgNWs.

Main Methods:

• Synthesis and characterization of ~70 nm diameter silver nanowires.
• Coating of AgNWs with nm-sized silica shells using a modified Stöber method.
• Characterization using transmission electron microscopy (TEM), dark-field microscopy, and electron-energy loss spectroscopy (EELS).
• Numerical simulations to support experimental findings.

Main Results:

• Homogeneous and smooth silica shells were achieved on the silver nanowires.
• Characterization confirmed the morphology and plasmonic resonances of individual coated nanowires.
• Experimental and simulation results demonstrated that the silica coating does not degrade plasmonic properties.

Conclusions:

• The developed controlled synthesis and coating approach enables precise distance control for silver nanowires.
• Silica-coated silver nanowires are suitable building blocks for integrated hybrid plasmonic systems.
• This method facilitates the development of advanced plasmonic devices and circuits.