Localized surface plasmons in structures with linear Au nanoantennas on a SiO₂/Si surface

Area of Science:

• * Plasmonics and Nanophotonics
• * Solid State Physics
• * Materials Science

Background:

• * Localized surface plasmons (LSPs) in metallic nanostructures exhibit unique optical properties.
• * Understanding LSP interaction with dielectric materials is crucial for nanophotonic device applications.
• * Silicon dioxide (SiO2) is a common dielectric material in semiconductor and photonic technologies.

Purpose of the Study:

• * To experimentally determine the penetration depth of LSPs into SiO2 layers.
• * To investigate the coupling between plasmonic excitations and optical phonons in SiO2.
• * To validate experimental findings with electromagnetic simulations.

Main Methods:

• * Fabrication of linear gold nanoantennas on Si substrates with varying SiO2 layer thicknesses.
• * Measurement of infrared absorption spectra to analyze plasmon behavior.
• * Electromagnetic simulations to model LSP penetration depth and plasmon-phonon interactions.

Main Results:

• * Experimentally determined LSP penetration depth into SiO2 was 20 ± 10 nm.
• * Simulated LSP penetration depths ranged from 12.9 to 30.0 nm, consistent with experimental data.
• * Observed new plasmon-phonon modes in infrared transmission spectra due to coupling, with frequencies accurately predicted by simulations.

Conclusions:

• * The study successfully quantified the LSP penetration depth in SiO2 using gold nanoantennas.
• * Experimental and simulation results show strong agreement, confirming the understanding of plasmon behavior.
• * The observed plasmon-phonon coupling provides insights into light-matter interactions at the nanoscale.