Edge geometry superconducting tunnel junctions utilizing an NbN/MgO/NbN thin film structure

US5099294A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Brian D. Hunt · Oroville, US
• Henry G. LeDuc · Pasadena, US

Key dates

• Filing date: Jan 16, 1991
• Grant date: Mar 24, 1992
• Expiry date: Jan 16, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S505/871

Abstract

An edge defined geometry is used to produce very small area tunnel junctions (30) in a structure with niobium nitride superconducting electrodes (14, 28) and a magnesium oxide tunnel barrier (24). The incorporation of an MgO tunnel barrier with two NbN electrodes results in improved current-voltage characteristics, and may lead to better junction noise characteristics. The NbN electrodes are preferably sputter-deposited, with the first NbN electrode deposited on an insulating substrate maintained at about 250.degree. to 500.degree. C. for improved quality of the electrode.