Comparative Analysis of Work Function Measurement Techniques Based on Scanning Probe Microscopy

Area of Science:

• Surface Science
• Materials Science
• Nanotechnology

Background:

• Accurate local work function measurements are crucial for understanding surface properties.
• Scanning probe techniques offer potential for quantitative work function determination.
• Comparing different methods is essential to establish reliable protocols.

Purpose of the Study:

• To compare the accuracy and reliability of three scanning probe techniques for local work function measurements.
• To evaluate I(z) spectroscopy, field-emission resonances (FER), and Kelvin probe force spectroscopy (KPFS).
• To determine the work functions of various metal surfaces, including superconducting Niobium.

Main Methods:

• Utilized I(z) spectroscopy, field-emission resonances (FER) with triangular-barrier extrapolation and numerical analysis, and Kelvin probe force spectroscopy (KPFS).
• Employed Ag(111) as a reference surface for method calibration.
• Applied techniques to Ir(111), Au(111), and superconducting Nb (111), (110), and oxygen-reconstructed phases.

Main Results:

• Demonstrated significant method dependence in work function measurements.
• I(z) spectroscopy exhibited high uncertainty and limited surface applicability.
• Numerical FER analysis provided consistent results, while KPFS offered the most direct and reliable determination after tip calibration.

Conclusions:

• Kelvin probe force spectroscopy (KPFS) is the most robust method for quantitative local work function measurements.
• Numerical FER analysis is a viable alternative, offering consistent results.
• Work functions for different surfaces and phases of Niobium were successfully extracted, highlighting method-specific outcomes.