Revisiting semicontinuous silver films as surface-enhanced Raman spectroscopy substrates

Area of Science:

• Analytical Chemistry
• Materials Science
• Nanotechnology

Background:

• Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for trace analyte detection.
• Semicontinuous metal films, fabricated via physical methods, are effective SERS substrates.
• Understanding substrate morphology is crucial for optimizing SERS performance.

Purpose of the Study:

• To investigate the impact of silver nanostructure morphology on SERS properties.
• To identify optimal film structures for enhanced SERS signal detection.
• To correlate film morphology with SERS enhancement factors.

Main Methods:

• Fabrication of semicontinuous silver films using electron beam physical vapor deposition.
• Characterization of film morphologies, ranging from isolated particles to continuous films.
• Evaluation of SERS performance using 4-aminothiophenol (4-ATP) as an analyte.

Main Results:

• SERS enhancement was highest for films composed of isolated silver structures below the percolation threshold.
• Substrates near the percolation threshold exhibited significantly lower SERS signals (approximately four times less).
• Film morphology critically influences the efficiency of SERS signal amplification.

Conclusions:

• Isolated silver nanostructures below the percolation threshold are superior SERS substrates.
• Optimizing nanostructure morphology is key to maximizing SERS sensitivity.
• This finding advances the development of advanced SERS analytical platforms.