Black Silicon: Breaking through the Everlasting Cost vs. Effectivity Trade-Off for SERS Substrates

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Black silicon (bSi) exhibits high light absorption across UV-vis and NIR ranges.
• Noble metal-plated bSi is promising for surface-enhanced Raman spectroscopy (SERS) substrates due to photon trapping.
• Developing cost-effective and efficient SERS substrates is crucial for sensitive analyte detection.

Purpose of the Study:

• To design and fabricate a black silicon surface profile for maximum Raman signal enhancement.
• To investigate the effectiveness of gold-plated bSi for SERS applications under NIR excitation.
• To demonstrate the potential of these substrates for sensitive detection in medicine, forensics, and environmental monitoring.

Main Methods:

• Fabrication of black silicon surface profiles using a cost-effective room temperature reactive ion etching method.
• Deposition of a nanometrically-thin gold layer onto the fabricated bSi surface.
• Numerical simulation to analyze plasmonic properties and identify optimal gold layer characteristics.

Main Results:

• The fabricated bSi surface profile, when coated with gold, provided maximum Raman signal enhancement under NIR excitation.
• The resulting bSi substrates were found to be reliable, uniform, low-cost, and effective for SERS-based analyte detection.
• Numerical simulations indicated that a defected gold layer on bSi increases plasmonic hot spots and NIR absorption cross-section.

Conclusions:

• Cost-effective, room-temperature fabrication of gold-plated bSi yields highly effective SERS substrates.
• These bSi substrates offer significant Raman signal enhancement, making them suitable for sensitive detection.
• The developed SERS substrates are essential for advancements in medical diagnostics, forensic analysis, and environmental monitoring.