The microstructure and electrical properties of thin films processed at low temperatures

thin films on (001) with excellent alignment suitable for microwave applications at 77 K have been fabricated using an ex situ anneal step in argon atmospheres at temperatures of . Surface resistance values as low as 400 (79 K, 10 GHz) and large-area critical current densities up to (77 K) have been achieved. In order to understand the relationship between the microstructure and electrical properties the films have been characterized by a variety of techniques, but especially transmission electron microscopy and allied methods. Microstructural features such as a-axis oriented grains, secondary phase particles, grain boundaries and surface outgrowths (especially of non-superconductor phases) have been found to have a significant effect on the surface resistance.