Exploiting cantilever curvature for noise reduction in atomic force microscopy

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Optical beam deflection is a standard technique for atomic force microscope (AFM) cantilever deflection detection.
• Angular detection noise density sets the fundamental limit for high-sensitivity AFM deflection sensing.

Purpose of the Study:

• To derive the first-order angular detection noise density for AFM.
• To investigate the role of cantilever radius of curvature in AFM noise.
• To demonstrate methods for reducing angular detection noise in AFM systems.

Main Methods:

• Developed a first-order theoretical derivation for angular detection noise density.
• Experimentally exploited cantilever curvature on a custom-built AFM.
• Utilized the optical properties of gold-coated cantilevers to enhance curvature effects.

Main Results:

• Identified cantilever radius of curvature as a critical, often overlooked, factor in AFM noise.
• Achieved a reduction in angular detection shot noise exceeding an order of magnitude.
• Quantified cantilever curvature's contribution to sensitivity variability (up to 45%) in commercial AFMs.

Conclusions:

• Cantilever curvature can be strategically utilized to minimize angular detection noise in AFM.
• Understanding and controlling cantilever curvature is essential for optimizing AFM sensitivity and reducing measurement variability.