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STABILIZATION OF Nb/Pb-ALLOY TUNNEL JUNCTIONS

IP.com Disclosure Number: IPCOM000047116D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Broom, RF: AUTHOR [+3]

Abstract

Most Josephson device circuits require that the essential parameters of a completed junction, e.g., the Josephson current and the junction quality factor Vm, remain constant. There should be no drift either in heating cycles of subsequent process steps or during storage at room temperature. It has now been found that the tunneling stability of Nb/Pb-alloy junctions can be greatly improved by the addition of a small amount of oxygen to the Pb-alloy forming the counter-electrode of the junction. The counter-electrode of Nb/Pb-alloy junctions may, e.g., consist of three sequential depositions of Pb (84 wt%), Au (4 wt%) and In (12 wt%). During the evaporation of the initial Pb film for the counter-electrode, carried out at room temperature, an oxygen partial pressure of 10-7 to 10-6 Torr is added as a low, uncritical background.

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STABILIZATION OF Nb/Pb-ALLOY TUNNEL JUNCTIONS

Most Josephson device circuits require that the essential parameters of a completed junction, e.g., the Josephson current and the junction quality factor Vm, remain constant. There should be no drift either in heating cycles of subsequent process steps or during storage at room temperature. It has now been found that the tunneling stability of Nb/Pb-alloy junctions can be greatly improved by the addition of a small amount of oxygen to the Pb-alloy forming the counter-electrode of the junction. The counter-electrode of Nb/Pb-alloy junctions may, e.g., consist of three sequential depositions of Pb (84 wt%), Au (4 wt%) and In (12 wt%). During the evaporation of the initial Pb film for the counter- electrode, carried out at room temperature, an oxygen partial pressure of 10-7 to 10-6 Torr is added as a low, uncritical background. This is sufficient to substantially improve the stability particularly with regard to the tunnel current.

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