In-Situ Fabrication, Processing And Characterization Of Superconducting Oxide Films

A. I. Braginski; J. Talvacchio; J. R. Gavaler; M. G. Forrester; M. A. Janocko

doi:10.1117/12.947476

23 August 1988 In-Situ Fabrication, Processing And Characterization Of Superconducting Oxide Films

A. I. Braginski, J. Talvacchio, J. R. Gavaler, M. G. Forrester, M. A. Janocko

Proceedings Volume 0948, High-Tc Superconductivity: Thin Films and Devices; (1988) https://doi.org/10.1117/12.947476
Event: Advances in Semiconductors and Superconductors: Physics and Device Applications, 1988, Newport Beach, CA, United States

Abstract

Surfaces of Y1Ba2Cu3O7 (YBCO) are known to react with H₂O and CO₂ in the ambient atmosphere. The in-situ approach to thin film fabrication and characterization in a closed system makes it possible to investigate the near-surface properties of superconducting YBCO films in the absence of such deleterious reactions. We have fabricated and analyzed superconducting, epitaxial YBCO films entirely or partly in-situ. Oxygen partial pressures during deposition ranged from < 10-9 torr to > 3 X 10^-4torr and temperatures from 400 to > 650Ã‚Â°C, producing either amorphous or crystalline deposits. We found that annealing of oxygen-deficient amorphous deposits in oxygen caused atomic segregation of Ba and Y to the surface with a corresponding depletion in Cu. This effect made near-surface layers nonsuperconducting even in the absence of H2O or CO₂. Fast heating to crystallization temperature minimized the segregation. Measurements of dc contact resistance, R , and I-V characteristics in cross-strip junctions of YBCO/Au/Nb and YBCO/Au/MgO/Nb indicated near-zero Rc and weak-link I-V characteristics which proved that the in-situ approach permits one to obtain superconducting YBCO film surfaces. In the case of crystalline film deposition at 650°C, the in-situ electron-diffraction of SrTiO₃ substrates and 40 to 100 Å thick YBCO films revealed epitaxial crystallization only on clean substrates.

Citation Download Citation

A. I. Braginski, J. Talvacchio, J. R. Gavaler, M. G. Forrester, and M. A. Janocko "In-Situ Fabrication, Processing And Characterization Of Superconducting Oxide Films", Proc. SPIE 0948, High-Tc Superconductivity: Thin Films and Devices, (23 August 1988); https://doi.org/10.1117/12.947476

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