Subsurface atomic force microscopy: towards a quantitative understanding

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Subsurface atomic force microscopy enables non-destructive imaging of deeply embedded micro- and nanoparticles.
• Understanding the contrast formation mechanism is crucial for interpreting these images.

Purpose of the Study:

• To investigate the contrast formation mechanism in subsurface atomic force microscopy.
• To compare finite element analysis and analytical study predictions with experimental observations.

Main Methods:

• Performed finite element analysis and analytical studies of ultrasound wave propagation through a sample.
• Calculated amplitude and phase variations on the sample surface.
• Modeled Rayleigh scattering of acoustic waves.

Main Results:

• Rayleigh scattering of acoustic waves was identified as the primary cause of measured contrast.
• Numerical models indicated contrast is independent of particle burial depth.
• Analytical models showed a 1/depth dependence for contrast.
• Significant discrepancies in particle width were observed between numerical and analytical calculations.

Conclusions:

• Both numerical and analytical models are essential for a comprehensive understanding of subsurface imaging.
• Reflections at sample interfaces and bulk damping significantly influence contrast formation and require careful consideration in modeling.