A compact, all-digital microwave impedance microscopy system with automatic baseline cancellation

Area of Science:

• Nanoscience and Nanotechnology
• Electrical Engineering
• Materials Science

Background:

• Microwave impedance microscopy (MIM) is a powerful technique for nanoscale electrical characterization.
• Existing MIM systems can be limited by noise and baseline reflections, particularly at low frequencies or high power.
• Digital control and advanced signal processing offer potential improvements in MIM performance.

Purpose of the Study:

• To present a compact, fully digitally controlled microwave impedance microscopy (MIM) system.
• To enhance MIM sensitivity and reduce noise through a novel digital cancellation technique.
• To demonstrate the system's capability for high-quality nanoscale imaging.

Main Methods:

• Implementation of a modular, surface-mount platform for the MIM system.
• Development of a high-resolution, digitally tunable cancellation line utilizing destructive interference.
• Application of a physics-informed cancellation algorithm for rapid, automated noise minimization.
• Utilizing a quasi-DC-coupled readout for contact- and tapping-mode imaging.

Main Results:

• The system achieves efficient suppression of baseline reflections, significantly reducing noise.
• A physics-informed algorithm minimizes residual power within seconds, eliminating manual adjustments.
• The system demonstrates high-quality MIM scans with a near-Johnson-noise-limited floor down to 4 kHz.
• Quasi-DC-coupled readout prevents saturation in both contact and tapping modes.

Conclusions:

• The developed compact, digitally controlled MIM system offers enhanced sensitivity and reduced noise.
• The digital cancellation line and algorithm provide a robust solution for challenging MIM measurements.
• This system enables high-fidelity nanoscale electrical characterization across various imaging modes.