Calibrated complex impedance and permittivity measurements with scanning microwave microscopy.

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Accurate nanoscale material characterization is crucial for advanced electronic devices.
• Scanning microwave microscopy (SMM) offers high-resolution imaging but requires precise calibration for quantitative analysis.
• Existing calibration methods for SMM can be complex and time-consuming.

Purpose of the Study:

• To develop a simplified, in situ calibration procedure for complex impedance measurements using SMM.
• To enable accurate dielectric quantification and analysis of capacitive and resistive properties of nanoscale materials.
• To validate the method on thin dielectric films and doped semiconductor samples.

Main Methods:

• Utilizing tip-sample approach curves for in situ calibration and extraction of complex impedance.
• Converting S11 reflection signals into quantitative capacitance and resistance images.
• Applying electrical tip-sample models for dielectric constant extraction and capacitance-voltage spectroscopy.

Main Results:

• Accurate dielectric constant (εr ≈ 4) determined for SiO2 films at 19.81 GHz.
• Capacitance-voltage spectroscopy revealed clear correlations with semiconductor depletion zones.
• Resistivity measurements showed a strong dependence on dopant density, ranging from 20 Ω to 20 kΩ.

Conclusions:

• The proposed in situ calibration procedure is simple, fast, and accurate for SMM.
• The method effectively quantifies dielectric and semiconductor properties at the nanoscale.
• This technique is versatile, applicable to various substrates and frequencies (1-20 GHz).