Improved design josephson junctions with hybrid nanostructured barriers

Abstract

New type of Josephson junctions with hybrid nanostructured barriers has been fabricated and investigated. Heterostructures consisting of superconducting MoRe electrodes with a critical temperature about 9 K and a silicon film with a thickness of several dozens of nm (sandwiched between them) were fabricated. The silicon layer was doped by tungsten with various atomic concentrations. By using an atomic force microscope we have investigated a relief of the every layer of the fabricated Josephson junction, as a result it has been demonstrated a possibility to observe a formation of the cluster structure of tungsten in the silicon layer in the Josephson junction barrier on a nano-sized level. Measured I-V curves of these junctions demonstrate that the well-known parameter of these junctions (named the characteristic voltage) has record values. The observation is explained as the fingerprint of “open” channels in the charge transmission due to resonance-percolating trajectories inside the strongly inhomogeneous silicon interlayer with metallic nanoclusters.