Surface Resistance Imaging with a Scanning Near-Field Microwave Microscope

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.Comment: 6 pages, 3 figures; for color versions of figures see www.csr.umd.edu/research/hifreq/micr_microscopy.htm