Reproducibility and controllability of critical current for ramp-edge interface-modified junctions

We have investigated the relationship between process parameters and juncti on characteristics (I-c, R-n) of interface-modified junctions (IMJs) made o n MgO substrates, and have derived empirical equations from the obtained re lationships. Thin and uniform tunnel barriers of IMJs were formed by ion ir radiation and annealing. We chose accelerating voltage (V-acc), etching tim e (t(etch)) and deposition temperature (T-dep) as the process parameters fo r the control of critical current (I-c). We prepared four different samples fabricated in the same conditions, and examined the reproducibility and co ntrollability of I-c. The obtained I(c)s were very close to the expected va lue, and the run-to-run 1 sigma -spread was 20% at 4.2 K. Furthermore, we c ould also control I-c of IMJ made on SrTiO3 substrates. (C) 2001 Elsevier S cience B.V. All rights reserved.