Trimming of High-Tc Bicrystal Josephson Junctions by Ozone and Vacuum Annealing

AbstractSpecific values of characteristic voltages IcRn and normal-state resistances Rn of high-Tc Josephson junctions (JJ) are often required for their THz applications in detection and spectroscopy. Recently, evolution of these electrical parameters of [001]-tilt YBa2Cu3O7-x bicrystal JJ after low-temperature ozone annealing has been studied. Here, we present the effect of ozone and vacuum annealing on the IV-curves of [100]-tilt YBa2Cu3O7-x bicrystal JJ. Annealing temperature Ta was varied from 100°C to 225°C. It was demonstrated, that annealing in ozone-oxygen mixture and in vacuum has an opposite effect on JJ parameters, and the changes were reversible at Ta up to 145°C. Ozone annealing at Ta=100°C resulted in up to 1.5 times decrease of Rn. After annealing in vacuum at higher Ta, a transition temperature Tc of JJ electrodes was reduced from 90K to 52K, and significant, multifold changes of IcRn and Rn were observed. Further annealing in ozone at Ta up to 225°C restored Tc and Rn almost to their initial values, but IcRnvalues couldn’t be increased above 20% of the initial value. The obtained results can be used for trimming of junction parameters after main fabrication procedure