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Annealing of Josephson Junction Devices

IP.com Disclosure Number: IPCOM000083308D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Basavaiah, S: AUTHOR [+5]

Abstract

Josephson junction devices containing lead-based alloy films as base electrodes experience markedly increased Josephson current densities, during storage at room temperature or during fabrication of the devices. In order to obtain desirable device performances, these junctions should be stabilized against such changes. The increase in the current density is probably caused by an alteration of the tunneling barrier, by a thermally activated process to a thermodynamically stable state. Consequently, the rate of change of the current density during storage can be brought within an acceptable range, by annealing of the tunneling barrier at an appropriate temperature.

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Annealing of Josephson Junction Devices

Josephson junction devices containing lead-based alloy films as base electrodes experience markedly increased Josephson current densities, during storage at room temperature or during fabrication of the devices. In order to obtain desirable device performances, these junctions should be stabilized against such changes. The increase in the current density is probably caused by an alteration of the tunneling barrier, by a thermally activated process to a thermodynamically stable state. Consequently, the rate of change of the current density during storage can be brought within an acceptable range, by annealing of the tunneling barrier at an appropriate temperature.

Annealing of junctions containing Pb alloys can occur at temperatures of 50 degrees - 70 degrees C for several hours. This results in less than a 1%/day change in the current density during subsequent storage at room temperature.

Annealing can also be used to tailor the Josephson current density J1, which is an important parameter in a design of memory and logic circuitry using Josephson junction devices. Current density J1 is a function of the tunnel barrier thickness and tunnel barrier height. Since J1 exponentially depends upon the barrier height and thickness, small variations in any of the fabrication parameters used to make the barriers will produce large variations in J1. Accordingly, it is very difficult to obtain a specified current density which is reprod...