Design and implementation of an automated low noise cryogenic characterization system for high-Tc Josephson junctions

Abstract

Since the discovery of high temperature superconductors, superconductivity became one of the fast emerging technologies being used in numerous applications where in many of these applications Josephson junctions form the basis for superconducting electronic devices and circuits. In order to use the Josephson junctions effectively and fabricate them reproducibly with the same properties, their characterization should be done where their main characterization is the current vs. voltage measurement. This study concentrates on the design and implementation of two automated low noise cryogenic characterization systems that let current vs. voltage, dynamic resistance vs. current, and resistance vs. temperature characterizations be done at temperatures ranging from 63.15K to 120K for the Josephson junctions. In this study, also the fabrication and preparation steps of different types of high-Tc Josephson junctions, such as step edge and bicrystal junctions of junction arrays, gradiometers’, and dc-SQUIDs’ for characterization, are explained. By using the established characterization systems, the current vs. voltage behaviors for different types of junctions could be measured and classified.