Improvement in Parameter Spreads of YBaCuO/PrBaCuO/YBaCuO Trilayer Junctions

An improvement in the distribution of junction properties for YBaCuO/PrBaCuO/YBaCuO trilayer junctions has been demonstrated. In order to ensure a uniform substrate temperature during the deposition of trilayer films, Al/Cu/Al stacked foils are introduced as a backing plate between the substrate and sample holder. Furthermore, the film composition is optimized to reduce the precipitated particles on the surface of the films. All the junctions with a barrier thickness of 35 nm and an area less than 100 µ m2 show RSJ-like current voltage characteristics with some excess current at 4.2 K. The 1-σ spreads of Josephson critical current density J c and normalized junction resistance R n A are obtained to be 34% and 25%, respectively, for 88 junctions on the same substrate. This result is comparable to the 1-σ spreads of ramp-edge type junctions.