A scanning mapping technique of surface resistance (Rs) using the sapphire dielectric resonator was developed and demonstrated for a 3-inch-diameter YBa2Cu3Oy film. The area of the 3-inch film was divided by 5 × 5 mm grid for scan, resulting in 101 measurement points. Values of Rs in the film varied from 2.9 to 3.8 mΩ at 22 GHz and 77 K. The distribution of Rs corresponded to that of the critical current density. Sampling of quality factors at each point was performed using non-contact measurement between film and sapphire. Since the airtight chamber was filled with dry N2 gas to avoid film degradation by frost and water during the warming process, perfect non-destructive measurement is realized. Fluctuation of distance between the surface of film and dielectric rod was monitored by resonance frequency. Errors in Rs caused by the fluctuation were calculated within ±0.01 mΩ. Furthermore, the system could detect a small (0.3 mm × 0.5 mm) scratch defect as well as the gradient of film thickness on Ag film. This technique is effective for inspection of large-area high temperature superconducting films for microwave applications.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering