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.
Type:
Grant
Filed:
January 16, 1991
Date of Patent:
March 24, 1992
Assignee:
The United States of America as represented by the Administrator of the National Aeronautics and Space Administration