Calibration method for complex permittivity measurements using s-SNOM combining multiple probe tapping harmonics.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Scattering-type scanning near-field optical microscopy (s-SNOM) offers high sensitivity for analyzing nanoscale material properties.
• Extracting complex permittivity from s-SNOM data is challenging due to complex probe-sample interactions, often requiring computationally intensive inverse problems.
• Existing black-box calibration methods are typically suited for static systems, not dynamic s-SNOM setups.

Purpose of the Study:

• To develop an advanced black-box calibration technique for s-SNOM.
• To address the limitations of existing methods in dynamic s-SNOM environments.
• To enable more accurate quantitative analysis of material permittivity.

Main Methods:

• Proposed an improved black-box calibration method for s-SNOM.
• Incorporated the effects of probe tapping and its harmonics into the calibration model.
• Accounted for the far-field background signal in the calibration process.
• Validated the method using mid-infrared s-SNOM spectroscopy on silicon microstructures.

Main Results:

• Successfully extracted complex permittivity from s-SNOM measurements.
• Demonstrated the method's effectiveness on silicon microstructures with varying doping levels.
• The improved calibration accurately accounts for dynamic effects like probe tapping.

Conclusions:

• The developed black-box calibration method enhances the quantitative accuracy of s-SNOM.
• This technique overcomes limitations of static calibration methods in dynamic s-SNOM measurements.
• Enables more reliable characterization of material permittivity at the nanoscale.