Estimation of Focused Helium Ion Beam Josephson Junction Width

Josephson junctions fabricated with a focused helium ion beam exhibit electrical properties that are strongly dependent on the size of the junction. The length of the junction, in the direction of the super-current, is one of the critical parameters. In this report, we compare three methods of estimating this critical feature, utilizing resistive and capacitive transport data and Monte Carlo ion implantation simulations. Our results find that the barrier is 3 ± 1 nm long and agree well with one another.