Extremely smooth YBCO-films on MgO with high critical current densities

✍ Scribed by F. Baudenbacher; K. Hirata; P. Berberich; H. Kinder; W. Assmann; H.P. Lang

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 318 KB
• Volume: 185-189
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)91213-n

✦ Synopsis

We have prepared segregation free, extremely smooth YBCO films on MgO substrates by our technique of thermal co-evaporation. The two key ingredients were selection of high quality substrates by RHEED, and a very close control of the stoichiometry: The absolute composition of the films was determined by heavy-ion-RBS with an accuracy of 1% for the content of each metal. Deviations from stoichiometry by 2 -3 % manifest themselves by characteristic surface morphologies while films with ideal stoichiometry reveal no surface structure at all with FE-SEM but a residual roughness of about 5 monolayers (5,5 nm) with STM. All films near stoichiometry have Te's of 90 K and jc'S of 3-10e A/era2 at 77 K.