Superconductor-normal-superconductor behavior of Josephson junctions scribed in Y1Ba2Cu3O7−δ by a high-brightness electron source

Abstract

We report a substantial improvement in the behavior of Josephson junctions scribed in Y1Ba2Cu3O7−δ films using a high-brightness field-emission electron gun source instead of a lower-brightness thermionic source. These junctions exhibit resistively shunted junction behavior over the entire temperature range from the coupling temperature to at least 4 K, a temperature window which can be larger than 55 K. Superconductor-normal-superconductor character is indicated by the exponential dependence of the critical current on temperature for all temperatures below 90 K. The data demonstrate that electron irradiation under these conditions produces a modified region which is completely normal above 4 K and is narrower in width than previously obtained.

Nanometer scale masked ion damage barriers in YBa/sub 2/Cu/sub 3/O/sub 7-δ/

“…INTRODUCTION reliable high temperature superconductor (HTS) junction fabrication technology for large-scale integration has been a long-standing requirement. One of the candidate technologies, at least in terms of junction quality and reproducibility, is the focused electron beam irradiation technique (FEBI) developed in Cambridge and elsewhere [1,2] in which the superconducting transition temperature (T c ) is locally suppressed by irradiation-induced damage. It was realized early on that much of the electron-induced damage is unstable at room temperature, and so the properties of early junctions changed rapidly with time.…”

Fabrication and Properties of High-$T_{\rm c}$ YBCO Josephson Junction and SQUID With Variable Thickness Bridges by Focused Ion Beam

“…To realize the practical high-transition temperature (high-) SQUIDs, various junctions technologies have been developed, including bicrystal, step-edge, ramp-edge, interface-modified, biepitaxial, step-edge superconductor-normal-superconductor, and locally damaged junctions [1]- [5]. Many efforts have been made to improve the junction fabrication technology to increase the reliability of fabrication and the reproducibility of junction parameters [4], [5]. The bicrystal grain boundary junctions have achieved excellent critical current and normal resistance product with acceptable reproducibility [1], [2].…”

Nature of the Josephson barrier in electron-beam-writtenYBa2Cu3OHinaus1, Rzchowski2, Davidson3 et al. 1997Phys. Rev. BSelf Cite8030View full textAdd to dashboardCite

“…6,7 Several groups 8,9 have shown that HTS films in which a narrow barrier with reduced T c has been created by focused electron-beam irradiation can display the Josephson effect in a limited temperature range below the electrode T c . The absence of cation disorder in these barriers makes them excellent candidates for interpreting the Josephson effect in HTS structures if the barrier properties can be quantified.…”

“…9 The samples were patterned for four-point measurements of four 2.5 m-wide by 10 mlong links per substrate, with twelve contact pads on the perimeter of the disk. A small slot cut in each substrate permitted in situ focusing and alignment of the electron beam.…”

“…Linear scribing doses ͑ϳ1ϫ10 12 electrons/m and 0.5 nA beam current͒ were similar to those used previously. 9 The focused electron beam has an approximate diameter of ϳ1.5 nm under these conditions. Scribing the electron beam across the width of the link produced a continuous nm-scale line of HTS material modified by oxygen displacement.…”