Investigation of properties of stacked-type interface-treated Josephson junctions fabricated with PrGaO/sub 3/ doping process

We have investigated how surface morphology of base YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) films affects the properties of the stacked-type interface-treated junctions (ITJ) with the PrGaO/sub 3/ (PGO) doping process. In the ITJs, the junction barriers are formed by Ar ion milling and subsequent annealing, without depositing artificial barriers. The PGO doping process was carried out for eliminating excess currents of the junctions. Our results suggest that the YBCO films suitable for the junctions should consist of similar size grains, and do not contain any precipitates. Furthermore, the morphology should not be changed after the Ar ion milling. The nine junctions fabricated on such a film exhibit the averaged critical current density (J/sub c/) on the chip of 9.0/spl times/10/sup 3/ A/cm/sup 2/, the small 1/spl sigma/ spread of 5.6% in the J/sub c/, and the averaged I/sub c/R/sub n/ product on the chip of 1.5 mV with overdamped characteristics at 4.2 K.