Browse Prior Art Database

Resistors for use in Josephson Circuitry Based on Nb Metallurgy

IP.com Disclosure Number: IPCOM000082391D
Original Publication Date: 1974-Nov-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Laibowitz, RB: AUTHOR

Abstract

Resistive elements are described for use in Josephson circuitry based on metallurgies Nb, Nb alloys and related materials, in both pure and doped form such as oxides and nitrides.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 81% of the total text.

Page 1 of 1

Resistors for use in Josephson Circuitry Based on Nb Metallurgy

Resistive elements are described for use in Josephson circuitry based on metallurgies Nb, Nb alloys and related materials, in both pure and doped form such as oxides and nitrides.

In Josephson circuitry, e.g., memory and logic arrays, resistive elements find application, e.g., as terminating resistors. The resistive elements are rugged, easily fabricated and compatible with Nb metallurgy.

Thin films of Nb have a depressed T(c) when the thickness falls below about 500 angstroms. Below about 200 angstroms, the films can be made normal at
4.2 degrees K. Thus, such a film can be used as a resistor in the Josephson circuitry. Length, width and thickness can be varied to provide the proper resistance. These films are continuous down to approx. 50 angstroms and are capable of carrying considerable current. The resistance vs. temperature characteristics are quite flat in this region over a wide range of temperature. Therefore, thermal variations will have no effect on their operations.

The presence of oxygen, even up to several per cent, has a similar effect. Films of NbO(x) where x << 1 have been made which are normal at 4.2 degrees K and yet conductive. They can be fabricated by admitting small amounts of oxygen to the evaporating chamber when the resistors are laid down. By varying the oxygen content, the resistivity of these films can be selected for the proper circuit values.

Various nitrogen compounds...