Title :
Fabrication and characterization of high temperature superconductor Josephson junctions with a novel device design
Author :
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.
Author_Institution :
Superconductivity Technol. Center, Los Alamos Nat. Lab., NM, USA
fDate :
6/1/1995 12:00:00 AM
Abstract :
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.<>
Keywords :
Josephson effect; Rutherford backscattering; X-ray diffraction; barium compounds; channelling; high-temperature superconductors; yttrium compounds; 77 K; DC SQUIDs; Rutherford backscattering channeling; SNS Josephson junctions; X-ray diffraction; YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// electrodes; YBa/sub 2/Cu/sub 3/O/sub 7/-YPrBa/sub 2/Cu/sub 3/O/sub 7/-YBa/sub 2/Cu/sub 3/O/sub 7/; chemical compatibility; current voltage characteristics; fabrication; gradient Pr-doped Y/sub 1-x/Pr/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-/spl delta//; growth; high temperature superconductor; microwave induced Shapiro steps; multilayer; normal-metal layer; resistively shunted junction; structural compatibility; thermal compatibility; voltage modulation; Chemicals; Doping profiles; Electrodes; Fabrication; High temperature superconductors; Josephson junctions; Superconducting devices; Superconducting epitaxial layers; Superconducting microwave devices; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
