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Preparation Of Fine Grained Pb-Bi Josephson Junction Counterelectrodes

IP.com Disclosure Number: IPCOM000049077D
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Murakami, M: AUTHOR [+2]

Abstract

This article describes a method for preparing Pb-Bi counterelectrode films having reduced grain size without degrading the junction electrical characteristics. A grain size reduction has been observed experimentally by adding Au and In to Pb-Bi films. Films consisting of 0.4 Mum of Pb-Bi covered with 2 nm of Au and 5 nm of In were deposited on substrates at 200(degree)K and then held at 0(degree)C for at least 3 hours to allow Au and In to diffuse into the grain boundaries of the Pb-Bi film before significant grain growth could occur. This technique produced films with an average grain size about half of that obtained for Pb-Bi films deposited at 0(degree)C.

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Preparation Of Fine Grained Pb-Bi Josephson Junction Counterelectrodes

This article describes a method for preparing Pb-Bi counterelectrode films having reduced grain size without degrading the junction electrical characteristics. A grain size reduction has been observed experimentally by adding Au and In to Pb-Bi films. Films consisting of 0.4 Mum of Pb-Bi covered with 2 nm of Au and 5 nm of In were deposited on substrates at 200(degree)K and then held at 0(degree)C for at least 3 hours to allow Au and In to diffuse into the grain boundaries of the Pb-Bi film before significant grain growth could occur. This technique produced films with an average grain size about half of that obtained for Pb-Bi films deposited at 0(degree)C. The novel features of this procedure include:

a) Thermal treatment in which films are deposited at 200 K

and then held at 0(degree)C for at least 3 hours to allow

the Au and In to diffuse before significant grain growth

occurs.

b) Deposition sequence in which Au and In are evaporated on

top of the Pb-Bi film. This leads to a distribution of

Au and In which reduces grain size without degrading

junction quality.

c) Use of Au/In ratio approximately that needed to form

AuIn(2) or slightly on the Au-rich side. Such a ratio

appears to provide optimal grain size reduction and

minimizes effects on junction quality.

The Pb-Bi-Au-In counterelectrode prepared by the present method offers the following advantages: (a) Average grain size is about half...