Reproducibility of niobium junction critical currents: statistical analysis and data

The authors present a statistical model to account for Josephson-junction critical current variability produced in integrated circuit processing. On the basis of data gathered from over a thousand junctions from the TRW superconducting integrated-circuit foundry line, it is shown that present niobium technology can produce junctions with critical currents identical to within a few percent, depending on junction size. Less than 2% (1 sigma ) spread critical currents were measured for 10 mu m junctions.>