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Large Output Josephson Devices and Superconducting Transistors

IP.com Disclosure Number: IPCOM000108510D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 56K

Publishing Venue

IBM

Related People

Jackson, TN: AUTHOR [+3]

Abstract

The output voltage and frequency response of Josephson junctions and transistors based on them are limited by the product of the junction critical current and resistance product, which is equal to or smaller than the superconducting energy gap of the electrode materials. Disclosed is a structure which extends this limit considerably.

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Large Output Josephson Devices and Superconducting Transistors

       The output voltage and frequency response of Josephson
junctions and transistors based on them are limited by the product of
the junction critical current and resistance product, which is equal
to or smaller than the superconducting energy gap of the electrode
materials. Disclosed is a structure which extends this limit
considerably.

      It is a well-established theoretical and experimental fact that
the product of the critical current and the normal resistance of a
Josephson junction is less than the energy gap of the electrodes, for
both tunnel junctions and various types of weak links (1).  This
limitation has important consequences for device applications.  For
example, voltage gain is less than unity in superconducting
transistors based on semiconductor-coupled weak links.

      It is known that the critical current-resistance product of
certain weak links based on semiconductors exceeds theoretical
values, even though the aforementioned theoretical limit is not
exceeded (2).  The structure of this invention is a device which
should allow this limit to be surpassed.  This invention, a
semiconductor weak link with a high link resistivity having extremely
high transparency Schottky contacts to the superconcucting
electrodes, is based on this experimental evidence and extrapolation
of existing theory.  Previous structures are based on the accepted
idea that the energy gap of the el...