Quantitative amplitude-modulation scanning Kelvin probe microscopy via the second eigenmode excitation

Area of Science:

• Surface Science
• Microscopy Techniques
• Materials Characterization

Background:

• Amplitude modulation scanning Kelvin probe microscopy (AM-SKPM) is a standard technique for measuring contact potential difference (CPD).
• Quantitative accuracy of AM-SKPM is often limited by crosstalk between the probe's cantilever and the sample surface.

Purpose of the Study:

• To significantly improve the quantitative accuracy of CPD measurements obtained via AM-SKPM.
• To demonstrate a novel method for reducing crosstalk artifacts in AM-SKPM.

Main Methods:

• Utilizing the second eigenmode of oscillation for exciting the SKPM probe.
• Analyzing the effect of the second eigenmode's stationary node on cantilever displacement and virtual work.
• Experimental validation using interdigitated electrodes and semiconductor heterojunctions (GaAs/GaN).

Main Results:

• Exciting the SKPM probe at its second eigenmode drastically improves the accuracy of CPD measurements.
• This method effectively reduces the crosstalk effect by partially canceling the virtual work done by the cantilever.
• Experimental results confirm enhanced accuracy on both calibration samples and practical material interfaces.

Conclusions:

• Driving the SKPM probe at its second eigenmode offers a robust solution to the crosstalk limitation in AM-SKPM.
• This technique provides more reliable and quantitatively accurate CPD measurements for surface potential analysis.
• The improved AM-SKPM method is applicable to various material systems, including semiconductor heterojunctions.