Sputtered a-silicon tunneling barriers for Nb-Nb Josephson junctions

Journal Article · Mon Nov 01 04:00:00 EST 1982 · IEEE Trans. Magn.; (United States)

DOI:https://doi.org/10.1109/TMAG.1982.1062214· OSTI ID:5994350

Smith, L N; Jillie, D W; Kroger, H; Thaxter, J B

The authors have developed an IC-compatible process for fabricating Josephson tunnel junctions, which uses dc magnetron-sputtered Nb films as both base and counterelectrodes, and rf-sputtered amorphous silicon as the tunneling barrier. Optical reflectivity measurements have been used to study the silicon barrier, and to allow precise determination of the barrier thickness. The Josephson current density varies exponentially -over several orders of magnitude -- with the barrier thickness. The product of the critical current and subgap resistance V /SUB m/ is constant over this wide range of current density. The specific capacitance of these junctions is about 2.5 ..mu..f/cm/sup 2/ at a current density of a few hundred A/cm/sup 2/. This is lower than the value for lead-alloy junctions, about 4.3 ..mu..f/cm/sup 2/, and is consistent with the measured thickness and dielectric constant of the a-Si barrier.

• Research Organization: Sperry Research Center, Sudbury, MA 01776
• OSTI ID: 5994350
• Journal Information: IEEE Trans. Magn.; (United States), Journal Name: IEEE Trans. Magn.; (United States) Vol. 18:6; ISSN IEMGA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALLOYS
AMORPHOUS STATE
CAPACITANCE
CRITICAL CURRENT
CURRENT DENSITY
CURRENTS
DIELECTRIC PROPERTIES
DIFFUSION BARRIERS
DIMENSIONS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELEMENTS
FABRICATION
JOSEPHSON JUNCTIONS
JUNCTIONS
LEAD ALLOYS
METALS
NIOBIUM
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
REFLECTIVITY
SEMIMETALS
SILICON
SPUTTERING
SUPERCONDUCTING JUNCTIONS
SURFACE PROPERTIES
THICKNESS
TRANSITION ELEMENTS
TUNNEL EFFECT