Epitaxial Nature of New Insulating Material BaSnO3 for YBa2Cu3Ox-SIS Junctions

Yasuo TAZOH  Shintaro MIYAZAWA  

IEICE TRANSACTIONS on Electronics   Vol.E79-C    No.9    pp.1260-1263
Publication Date: 1996/09/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Toward Digital and Analog Applications of Superconductors)
Category: Device technology
insulating material,  surface coverage,  wetability,  SIS,  

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BaSnO3 is proposed as a new insulating material with good surface coverage of the lower superconductor electrode for superconductor/insulator/superconductor (SIS) tunnel junctions made of high-Tc superconductor YBa2Cu3Ox (YBCO). This paper reports on investigation of the epitaxial nature of BaSnO3 on YBCO thin films and YBCO/BaSnO3 /YBCO trilayer formation that are grown in situ by reactive co-evaporation in oxygen radicals. Investigation was done by reflection high-energy electron diffraction (RHEED), atomic force microscopy (AFM), and X-ray diffraction (XRD). these observations confirm that (001)-oriented YBCO and (100)-oriented BaSnO3 thin films with atomically smooth surfaces grow epitaxially on each other. In addition, cross-sectional transmission electron microscopy (TEM) observation reveals that an approximately 4-nm-thick layer of BaSnO3 perfectly covers the lower YBCO thin film surface steps to a height of 1 to 2 unit cells of YBCO. The zero-resistance critical temperature Tc zero of both the upper and the lower YBCO thin films is higher than about 86 K.