T. Makita et al., Fabrication and characterization of Y-Ba-Cu-O and Nd-Ba-Cu-O ramp-edge junctions with an interface-modified barrier, IEEE APPL S, 11(1), 2001, pp. 155-158
The fabrication process for YBa2Cu3O7-delta (YBCO) ramp-edge junctions with
an interface-modified barrier has been studied. The conditions of electron
cyclotron resonance (ECR) ion etching and following annealing treatment we
re optimized by evaluating the mean roughness of the ramp surface using ato
mic force microscope (AFM) observation. We could obtain resistively-shunted
junction (RSJ) type current-voltage characteristics for the junctions with
the counterelectrode YBCO layer deposited at temperatures lower than 720 d
egreesC, while the deposition temperature higher than 755 degreesC resulted
in a high-J(c) superconducting contact. The junctions exhibited an IcRn pr
oduct of 1.0 - 1.9 mV and magnetic field modulation of I-c more than 90 % a
t 4.2 K, By applying the optimum etching condition to a NdBa2Cu3O7-delta (N
BCO) base electrode and employing a slightly higher annealing and depositio
n temperature, YBCO/NBCO ramp-edge Josephson junctions with a similar IcRn
product were successfully obtained.