We present electrical characterization data of sputtered Nb/a-Si/Nb Josephson junctions (JJs) for high-speed and high-density superconducting circuits. Junctions were studied with critical current densities ( ) ranging from 0.01 to 3 mA/μm2 at 4 K. For junctions deposited at room temperature and processed to a maximum temperature of 150 °C, the dependence of on barrier thickness d is exponential, , with constant over the entire range of values studied. Junctions were annealed at temperatures up to 300 °C to study changes in their electrical properties and possible compatibility with high temperature fabrication processes. Current–voltage characteristics, critical current uniformity, critical current modulation with in-plane magnetic field, and sub-gap resistance behavior of these junctions were measured at 4 K and demonstrate that the junction properties do not degrade with annealing. These data indicate that Nb/a-Si/Nb JJs are a potential candidate for higher speed and higher density superconducting circuits.
Nb/a-Si/Nb Josephson junctions for high-density superconducting circuits
Note: This paper is part of the APL Special Collection on Advances in Superconducting Logic.
David I. Olaya, John Biesecker, Manuel A. Castellanos-Beltran, Adam J. Sirois, Peter F. Hopkins, Paul D. Dresselhaus, Samuel P. Benz; Nb/a-Si/Nb Josephson junctions for high-density superconducting circuits. Appl. Phys. Lett. 1 May 2023; 122 (18): 182601. https://doi.org/10.1063/5.0148250
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