Formation of Armored Silicon Nanowires Array via High-Repetition-Rate Femtosecond Laser Oxidation for Robust...

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Superhydrophobic nanostructures are crucial for sensitive surface-enhanced Raman scattering (SERS) detection due to dense hotspots and high concentration efficiency.
• However, their poor mechanical strength limits practical applications by causing damage and loss of functionality.

Purpose of the Study:

• To develop a mechanically robust SERS substrate with superhydrophobic properties for reliable and sensitive detection.
• To investigate the fabrication and performance of an armored superhydrophobic silicon nanowires array.

Main Methods:

• Fabrication of an armored nanowires array using femtosecond laser oxidation to create a micro/nanocross-scale oxide mask.
• Analysis of nanoparticle masking mechanisms during deep reactive ion etching (DRIE) for silicon nanowire formation.
• Characterization of superhydrophobicity (contact angle) and SERS performance (detection limit, enhancement factor).

Main Results:

• The armored nanowires array achieved a contact angle of 158°, indicating excellent analyte enrichment.
• Demonstrated a low detection limit of 10^-13 M for Rhodamine 6G and a high enhancement factor (EF) of 4.35 × 10⁹.
• The substrate maintained superhydrophobicity and stable SERS signal enhancement after mechanical stress tests.

Conclusions:

• The armored superhydrophobic silicon nanowires array offers a robust and highly sensitive platform for SERS detection.
• This durable nanostructure overcomes the limitations of conventional SERS substrates, showing promise for diverse analytical applications.