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Epitaxial Insulating Cross Over for High TC Devices

IP.com Disclosure Number: IPCOM000109156D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 64K

Publishing Venue

IBM

Related People

Gambino, RJ: AUTHOR [+4]

Abstract

Disclosed is means for providing an insulating layer between lines or layers of high Tc superconductor that cross over each other. The superconducting material, for example, YBa2Cu3O7 referred to a 123, is epitaxially deposited with the c crystallographic axis oriented perpendicular to the intended direction of current flow in both superconducting lines. The insulating layer maintains this epitaxial relationship throughout the thickness of the device. The epitaxial growth ensures that there are no grain boundaries or similar defects along the current path. Grain boundaries act as weak links so they limit the critical current and generate noise. Noise generation is especially harmful because it degrades the performance of SQUID detectors, for example, connected to a superconducting pick-up coil.

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Epitaxial Insulating Cross Over for High TC Devices

      Disclosed is means for providing an insulating layer between
lines or layers of high Tc superconductor that cross over each other.
The superconducting material, for example, YBa2Cu3O7 referred to a
123, is epitaxially deposited with the c crystallographic axis
oriented perpendicular to the intended direction of current flow in
both superconducting lines.  The insulating layer maintains this
epitaxial relationship throughout the thickness of the device.  The
epitaxial growth ensures that there are no grain boundaries or
similar defects along the current path.  Grain boundaries act as weak
links so they limit the critical current and generate noise.  Noise
generation is especially harmful because it degrades the performance
of SQUID detectors, for example, connected to a superconducting
pick-up coil.  Cross overs are needed in these devices in order to
make multiturn coils and transformers.  In addition, there are other
applications of sandwich or multilayer structures in high Tc
circuitry that require epitaxial, high critical current materials on
insulating films, for example, junctions, vias and gate structures.

      In the prior art, SrTiO3 was used as the insulating film in
cross-overs.  However, SrTiO3 is difficult to grow epitaxially on 123
because of its refractory nature and because of lattice constant
mismatch.  Another problem is that the high deposition temperature
needed for epitaxial grow...