New method for electrostatic force gradient microscopy observations and Kelvin measurements under vacuum

Area of Science:

• Surface science
• Nanotechnology
• Atomic Force Microscopy

Background:

• Observing electrostatic force gradients is crucial for understanding surface properties.
• Existing methods may have limitations in resolution or parallel imaging capabilities.
• Atomic Force Microscopy (AFM) is a powerful tool for nanoscale surface analysis.

Purpose of the Study:

• To demonstrate the observation of both DC and AC electrostatic force gradients.
• To develop a method for parallel surface voltage or Kelvin imaging with AFM.
• To explain the experimental observations using a theoretical model.

Main Methods:

• Utilizing amplitude-controlled Atomic Force Microscopy (AFM) under secondary vacuum.
• Employing a double-pass method to measure phase shifts.
• Exploring different flexure mode orders and electrical frequencies.
• Developing a theoretical model based on linear mechanical oscillator behavior.

Main Results:

• Successfully observed both DC and AC electrostatic force gradients.
• Experimental phase shifts were explained by the theoretical model.
• Achieved parallel surface voltage or Kelvin imaging concurrent with morphology.
• Attained an RMS noise level in the millivolt range for voltage imaging.

Conclusions:

• The developed AFM method enables simultaneous measurement of surface topography and electrostatic potential.
• The theoretical model accurately describes the experimental phenomena.
• This technique offers high-resolution surface voltage mapping with low noise.