Improving ion irradiated high Tc Josephson junctions by annealing: The role of vacancy-interstitial annihilation

The authors have studied the annealing effect in the transport properties of high Tc Josephson junctions (JJs) made by ion irradiation. Low temperature annealing (80°C) increases the JJ coupling temperature (TJ) and the IcRn product, where Ic is the critical current and Rn the normal resistance. They have found that the spread in JJ characteristics can be reduced by sufficient long annealing times, increasing the reproducibility of ion irradiated Josephson junctions. The characteristic annealing time and the evolution of the spread in the JJ characteristics can be explained by a vacancy-interstitial annihilation process rather than by an oxygen diffusion one.