Quantitative Evaluation of SERS-Active Ag Film Nanostructure by Atomic Force Microscopy

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) is crucial for nanoscale material characterization.
• Reliable image analysis algorithms are needed for accurate nanostructural information extraction from AFM data.
• Thin metal films, like silver (Ag), exhibit unique properties influenced by their nanostructure.

Purpose of the Study:

• To evaluate the reliability of an image analysis algorithm for AFM of thin metal films.
• To determine optimal fitting parameters for quantitative nanostructural analysis.
• To investigate the influence of scanning parameters on AFM measurements of Ag films.

Main Methods:

• Comparison of algorithm analysis with manual analysis and transmission electron microscopy (TEM).
• Optimization of parameters: low-pass filtering, particle identification grid size, and shape-fitting model (hemispheroidal).
• Systematic examination of scanning parameters: scan rate, scan size, applied load, and humidity.

Main Results:

• Optimal parameters include low-pass filtering, a 5x5 grid for maxima identification, and a hemispheroidal fit.
• Tip geometry significantly impacts height measurements due to particle proximity.
• Increased scan rate reduces particle count and alters apparent dimensions; specific forces cause surface damage or subtle morphology changes.

Conclusions:

• The developed algorithm provides reliable nanostructural information for thin metal films.
• Understanding the influence of tip geometry and scanning parameters is critical for accurate AFM measurements.
• Ag film surfaces exhibit homogeneous nanostructure over large areas under optimized imaging conditions.