Integration density of ion-damaged barrier Josephson junction and circuits

Abstract

We investigate on the integration density limit of the superconducting technology for Josephson devices and circuits based on ion-damaged barrier. This technology is suitable for very large integration of superconducting circuits as the footprint of the Josephson junction is of the order of 40 nm by 2 μm. Series arrays of Josephson junction can be designed for high voltage amplitude at the device terminals.We have fabricated single Josephson junctions and arrays of 2 and/or 10 Josephson junctions connected in series with equal spacing. This spacing was varied on different devices from 100 nm to 1.6 μm. We observe a strong change in the parameters characterizing the DC transport in the arrays with the highest density of the Josephson junctions. It shows that the scaling behavior of Josephson array DC properties strongly depends on the distance separating 2 consecutive Josephson junctions. We discuss the origin of these effects presumably due to defects created at long distance during the ion irradiation process. Comparison of magnetic field responses for an array and single Josephson junctions shows a reduction of the Meissner effect in the array.