Complexes of Parallel Grain Boundaries in YBa2Cu3O7 Film for Josephson Junction Chains and Arrays

Abstract

Substrates consisting of five parallel planar grain boundaries (GBs), oriented perpendicular to the surface and spaced by several micrometers, have been grown by solid-phase bonding of fianite crystals in order to obtain large complexes of closely spaced bicrystal Josephson junctions based on high-temperature superconductor (HTSC) films. The substrates had a crystallographic orientation (100) and dimensions of 1.0 × 10.0 × 10.0 mm3. All GBs were of symmetrical type, and their lattices were rotated by 12° in opposite directions around the axis perpendicular to the surface. The distance between GBs in a packet complex was 15 µm, and this value was maintained with an error of no more than 1 µm along their entire length of 10 mm. The deviation of the shape of all five GBs from an ideal geometric plane was within 1 µm along their entire length. Films of HTSC YBa2Cu3O7 with inheritance of GBs were grown on these substrates. Structures of two types were formed on the films using lithography. It is shown that the use of these fianite substrates in HTSC-based devices of cryogenic electronics increases significantly the density of bicrystal Josephson junctions; reduces several times the total length of superconducting lines connecting these junctions; and, correspondingly, decreases significantly the inductive resistance of these circuits and improves their electrical characteristics in comparison with the structures having similar functions but based on one or two parallel GBs.