The Effects of Sample Tilt on Atomic Force Microscopy Deflections.

Area of Science:

• Surface science
• Nanotechnology
• Materials science

Background:

• Atomic Force Microscopy (AFM) relies on measuring forces between a probe and sample via cantilever deflection.
• Existing AFM models often assume perfect sample leveling, which is rarely achieved in practice.
• Both sample and cantilever tilt can affect deflection measurements, particularly in the approach-to-contact phase.

Purpose of the Study:

• To computationally and experimentally investigate the effects of sample and cantilever tilt on AFM deflection-distance curves.
• To analyze the influence of tilt on both the approach-to-contact (AtC) and pull-off (PO) portions of the curve.
• To evaluate the validity of a new AFM model that incorporates tilt effects and surface roughness.

Main Methods:

• Utilized a recently developed computational model accounting for attractive/repulsive forces and surface roughness.
• Performed AFM experiments using probes of two sizes and a sapphire substrate.
• Varied sample tilt angles systematically during experiments to observe deflection changes.

Main Results:

• Experimental results showed good agreement with model predictions.
• Pull-off (PO) deflections decreased with increasing sample tilt angle.
• Approach-to-contact (AtC) deflections were largely unaffected by sample tilt, except at significant angles.

Conclusions:

• Sample tilt has a negligible effect on AtC deflections and minimal impact on PO deflections when the sample is reasonably leveled.
• The developed model accurately predicts the influence of tilt on AFM measurements.
• Optimized sample leveling in AFM experiments is crucial for reliable deflection data.