On-chip surface-enhanced Raman spectroscopy using nanosphere-lithography patterned antennas on silicon nitride...

Area of Science:

• Nanophotonics
• Spectroscopy
• Materials Science

Background:

• Miniaturized chips integrating nanoplasmonic antennas with silicon nitride waveguides enable surface-enhanced Raman spectroscopy (SERS) for high-throughput assays.
• Current fabrication methods using electron-beam lithography are complex and limit the use of integrated photonics platforms.

Purpose of the Study:

• To demonstrate an electron-beam-free fabrication method for nanoplasmonic antennas on silicon nitride waveguides.
• To optimize these integrated devices for enhanced SERS performance at visible and near-infrared wavelengths.

Main Methods:

• Utilized nanosphere lithography for fabricating gold nanotriangles on deep-UV patterned silicon nitride waveguides.
• Optimized localized surface-plasmon resonance for Raman excitation at 785 nm.

Main Results:

• Achieved a SERS substrate enhancement factor of 2.5 × 10⁵.
• Demonstrated that SERS signal excited and collected through the waveguide is comparable to free-space excitation with a high NA objective.

Conclusions:

• Developed a simplified, electron-beam-free fabrication process for integrated SERS chips.
• The fabricated devices offer high sensitivity and efficient signal collection via on-chip photonics, paving the way for broader adoption.