Fabrication and characterization of high temperature superconductor Josephson junctions with a novel device design

• Published in: IEEE transactions on applied superconductivity 1995-06, Vol.5 (2), p.2103-2106
• Main Authors: Jia, Q.X., Wu, X.D., Foltyn, S.R., Reagor, D., Hawley, M., Springer, K.N., Tiwari, P., Mombourquette, C., Houlton, R.J., Campbell, I.H., Kung, H., Mitchell, T.E., Peterson, D.E.
• Format: Article
• Language: English
• Subjects: Chemicals; Doping profiles; Electrodes; Fabrication; High temperature superconductors; Josephson junctions; Superconducting devices; Superconducting epitaxial layers; Superconducting microwave devices; Voltage
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/77.402998

A unique normal-metal (N) layer construction was used to fabricate high temperature superconducting (S) YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// SNS Josephson junctions. The normal-metal included a gradient Pr-doped Y/sub 1-x/Pr/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta// layer which was composed of a light doping (x=0.1) next to both YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// electrodes, a slightly higher doping (x=0.3) towards the center, and a doping concentration of x=0.5 in the middle of the N-layer. A gradient of the doping profile of the N-layer instead of an abrupt one provides good thermal, structural, and chemical compatibility between adjacent regions. The multilayer configuration of the gradient Pr-doped N-layers on YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// showed good growth structure as confirmed by X-ray diffraction and Rutherford backscattering channeling tests. The SNS junctions fabricated in such a way showed resistively shunted junction current vs voltage characteristics above 77 K. Microwave induced Shapiro steps above 77 K and voltage modulation of dc SQUIDs at 77 K were both demonstrated with this technology.< >