Fabrication of thin-film-type Josephson junctions using a Bi-Sr-Ca-Cu-O /Bi-Sr-Cu-O/Bi-Sr-Ca-Cu-O structure

Thin-film Josephson junctions with normal metal barriers using a Bi-based high Tc oxide superconductor were successfully fabricated. Bi2Sr2Ca1Cu2Ox films were used for both superconducting electrodes and Bi2Sr2Cu1Oy for the barrier layer. The junction area of 20×40 μm2 was defined by photolithography and Ar ion milling. These S/N/S-type junctions clearly exhibited the ac Josephson effect under the irradiation of radio frequency waves of 12 GHz and more than 20 Shapiro steps were observed.