Josephson junction element

Abstract

Abstract PURPOSE:To reduce the electrostatic capacity of the barrier layer as well as to contrive improvement in switching speed of the titled element by a method wherein the barrier layer is formed as an Si nitride from the beginning. CONSTITUTION:An Nb lower electrode 2 of approximately 300nm in thickness is selectively formed by vapor-deposition on a saphire substrate 1, an aperture is provided on the SiO2 film 3 of 300nm in thickness, an Si nitride of 8nm or thereabout in thickness is provided by performing a sputtering method, and a barrier layer 4 is formed by oxidization in the dried air of 50Pa at 60 deg.C. A Pb upper electrode 5 of 100nm in thickness is then vapor-deposited on the above. According to this constitution, short-circuit is prevented because the Si and Nb at the pinhole part of the barrier 4 are oxidized, thereby generating no denaturation due to oxidization, while the reproducibility of the element characteristics is remarkably improved, and the electrostatic capacity is reduced to approximately one tenth of that of the Pb and Nb oxide heretofore in use, thereby enabling to reduce the switching speed.

Inventors

• 👤 Juichi Nishino
• 👤 西野　寿一
• 👤 Mikio Hirano
• 👤 幹夫 平野
• 👤 Junji Shigeta
• 👤 淳二 重田

Bibliographic Details