Edge geometry superconducting tunnel junctions utilizing an NbN/MgO/NbN thin film structure
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorsBrian D. Hunt, Henry G. LeDuc
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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.
Claims19
A superconducting tunnel junction device comprising a tunnel junction region comprising MgO film having a thickness ranging from about 5 to 30 .ANG. and sandwiched between two electrodes comprising NbN, each electrode bounded by upper and lower plane surfaces, said MgO film formed on a portion of a side surface of one of said NbN electrodes, said side surface comprising that smaller area surface between said two plane surfaces, each having a larger area than said side surface.
A superconducting tunnel junction device comprising a tunnel junction region consisting essentially of an MgO film having a thickness ranging from about 5 to 30 .ANG. and sandwiched between two electrodes consisting essentially of NbN, each electrode bounded by upper and lower plane surfaces, said MgO film formed on a portion of a side surface of one of said NbN electrodes, said side surface comprising that smaller area surface between said two plane surfaces, each having a larger area than said side surface, said electrodes formed on an insulating substrate.
Dependencies are inferred from the claim text.