Title :
Submicron NbN/MgO/NbN Josephson tunnel junctions and their application to the logic circuit
Author :
Aoyagi, M. ; Nakagawa, H. ; Kurosawa, I. ; Takada, S.
Author_Institution :
Electrotechnical Lab., Ibaraki, Japan
Abstract :
An improved fabrication process for submicron NbN/MgO/NbN Josephson tunnel junctions has been developed. By introducing a contact layer between the junction and the wiring layer, the critical current of the wiring above the junction was considerably enhanced. A logic circuit composed of four-junction logic gates was fabricated using 0.9- mu m-square junctions. Logic delay measurement was successfully achieved with a minimum logic delay of 3.6 ps/gate and a wide operating margin of +or-17% within 50 gates.<>
Keywords :
magnesium compounds; niobium compounds; sputter deposition; superconducting junction devices; superconducting logic circuits; superconducting thin films; Josephson tunnel junctions; NbN-MgO-NbN tunnel junction; RF magnetron sputtering; contact layer; critical current; fabrication process; four-junction logic gates; logic circuit; logic delay; submicron devices; Delay; Electrodes; Fabrication; Josephson junctions; Logic circuits; Logic devices; Resists; Semiconductor films; Substrates; Wiring;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
