Low-Capacitance Josephson Junctions
A. P. Shapovalov$^{1,2}$, P. Febvre$^3$, U. Yilmaz$^3$, V. I. Shnyrkov$^4$, M. O. Belogolovskii$^{1,5}$, and O. A. Kordyuk$^{1,4}$
$^1$G. V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine, 36 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
$^2$V. М. Bakul Institute for Superhard Materials of the N.A.S. of Ukraine, 2 Avtozavodska Str., UA-04074 Kyiv, Ukraine
$^3$Université Savoie Mont Blanc, IMEP-LAHC, Campus Scientifique, F-73376 Le Bourget du Lac Cedex, France
$^4$Kyiv Academic University of the N.A.S. and M.E.S. of Ukraine, 36 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
$^5$Vasyl’ Stus Donetsk National University, 21 600-Richchya Str., UA-21021 Vinnytsia, Ukraine
Received 02.12.2019; final version — 13.02.2020 Download PDF
Abstract
The Josephson effect, as an example of a macroscopic quantum phenomenon, reveals itself in the three-layer heterostructures formed by two superconductors coupled by a weak link that usually consists of a 1–2 nm-thick insulating barrier. The traditional way of modelling such-systems’ dynamics is based on an equivalent circuit that comprises three parallel elements: a pure superconducting element with a certain supercurrent-versus-Josephson phase difference dependence, a resistor $R$, and a capacitor $C$. In this short review, we analyse the practical problem of reducing the junction capacitance while maintaining or slightly impairing other characteristics. Some arguments are presented to explain why the capacitance should be suppressed and how it will affect performance of superconducting quantum interference devices (SQUIDs) and digital electronics circuits. As a solution for low-capacitance junctions, we propose a weak link made of an amorphous-silicon interlayer doped with nanoscale metallic drops between the two superconducting Mo–Re-alloy electrodes.
Keywords: Josephson junctions, RCSJ model, low capacitance, doped semiconductor barriers, Mo–Re-alloy electrodes, SQUID, SFQ logic.
Citation: A. P. Shapovalov, P. Febvre, U. Yilmaz, V. I. Shnyrkov, M. O. Belogolovskii, and O. A. Kordyuk, Low-Capacitance Josephson Junctions, Progress in Physics of Metals, 21, No. 1: 3–25 (2020)