Surface Resistance Imaging with a Scanning Near-Field Microwave Microscope

TL;DR

This paper presents a method for imaging surface resistance using a scanning near-field microwave microscope that detects frequency shifts related to local sample properties with high sensitivity.

Contribution

It introduces a technique to map sheet resistance by correlating frequency shifts in a resonant microwave system, enabling high-sensitivity measurements.

Findings

Achieved sensitivity to frequency shifts of 1 part in 50,000

Demonstrated mapping of surface resistance with a simple model

Utilized feedback circuit for stable frequency tracking

Abstract

We describe near-field imaging of sample sheet resistance via frequency shifts in a resonant coaxial scanning microwave microscope. The frequency shifts are related to local sample properties, such as surface resistance and dielectric constant. We use a feedback circuit to track a given resonant frequency, allowing measurements with a sensitivity to frequency shifts as small as one parts in 50000 for a 30 ms sampling time. The frequency shifts can be converted to sheet resistance based on a simple model of the system.