Open-loop amplitude-modulation Kelvin probe force microscopy operated in single-pass PeakForce tapping mode

Area of Science:

• Surface science
• Nanotechnology
• Scanning probe microscopy

Background:

• Kelvin probe force microscopy (KPFM) measures surface potential.
• Closed-loop (CL) KPFM variants (AM-KPFM, FM-KPFM) report only the final contact potential difference.
• CL KPFM typically requires a two-pass scan to avoid sample contact.

Purpose of the Study:

• To develop a single-pass open-loop (OL) AM-KPFM mode integrated with PeakForce Tapping (PFT).
• To improve the accuracy of KPFM measurements by accounting for cantilever contributions.
• To directly correlate electrical measurements with topography.

Main Methods:

• Implementation of a novel OL AM-KPFM mode within the PFT scanning mode.
• Applying electrical modulation only during the separation phase between PFT tip-sample contacts.
• Recording detailed cantilever response to bias stimulation for analysis.

Main Results:

• Simultaneous acquisition of topographical and electrical data in a single pass.
• Avoidance of contact and tunneling discharges by modulating during tip retraction.
• Accurate separation and removal of the cantilever's contribution to the measured potential.
• Achieved measurement accuracy comparable to CL FM-KPFM.

Conclusions:

• The new single-pass OL AM-KPFM mode offers enhanced accuracy and efficiency.
• This method provides a direct correlation between electrical properties and surface topography.
• The technique represents a significant advancement for surface potential measurements using AFM.