Microstructural studies of high-T/sub c/ superconducting Josephson junctions to understand junction properties
Transmission electron microscopy (TEM) is applied to the study of the relationship between the microstructures and the electrical properties of Josephson junctions. Typical microstructures for several artificial barrier junctions and grain boundary (GB) junctions are reviewed. In the case of artificial barrier junctions, it was found that the barrier layer coverage can be enhanced by using a-axis oriented bottom electrodes and homoepitaxy growth. TEM observations of multi-layer junctions with PrBa/sub 2/Cu/sub 3/O/sub y/ (PrBCO) or YBa/sub 2/Fe/sub 3/O/sub y/ (YBFeO) barrier layers grown by quasi-homoepitaxy showed prefect coverage and good crystallinity. Liquid phase-epitaxy was successfully used to obtain large single facet GBs over 50 pin by growing YBa/sub 2/Cu/sub 3/O/sub y/ (YBCO) films on bicrystal substrates. Microstructures and atomic arrangements of these straight bicrystal GBs are presented.