Title :
Microstructural studies of high-T/sub c/ superconducting Josephson junctions to understand junction properties
Author :
Wen, J.G. ; Usagawa, Tsuyoshi ; Takagi, T. ; Ishimaru, Y. ; Enoloto, Y. ; Koshizuka, N.
Author_Institution :
Supercond. Res. Lab., ISTEC, Tokyo, Japan
fDate :
6/1/1999 12:00:00 AM
Abstract :
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.
Keywords :
Josephson effect; barium compounds; bicrystals; grain boundaries; high-temperature superconductors; interface structure; liquid phase epitaxial growth; transmission electron microscopy; yttrium compounds; 50 mum; PrBa/sub 2/Cu/sub 3/O; PrBa/sub 2/Cu/sub 3/O/sub y/; TEM; YBCO films; YBa/sub 2/Cu/sub 3/O; YBa/sub 2/Cu/sub 3/O/sub y/; YBa/sub 2/Fe/sub 3/O; YBa/sub 2/Fe/sub 3/O/sub y/; a-axis oriented bottom electrodes; artificial barrier junctions; atomic arrangements; barrier layer coverage; bicrystal substrates; crystallinity; electrical properties; grain boundary; high-T/sub c/ superconducting Josephson junctions; homoepitaxy growth; junction properties; liquid phase-epitaxy; microstructural studies; transmission electron microscopy; Crystal microstructure; Crystallization; Josephson junctions; Milling; Nonhomogeneous media; Substrates; Superconductivity; Transistors; Transmission electron microscopy; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on