Planar S/N/S Josephson junctions using multi-layer Bi system

This paper reports on planar S/N/S Josephson junctions that were fabricated by multi- layered thin films of Bi-based high-Tc oxide superconductors. Two Bi2Sr2Ca1Cu2Ox films and Bi2Sr2Cu1Oy film were successively layered as superconducting electrodes and normal conducting buffer layer, respectively. These films were epitaxially deposited on (100) MgO substrate by in-situ process of RF magnetron sputtering. Micro junction areas were defined by photo-lithography and Ar ion milling. These S/N/S type junctions clearly exhibited the AC Josephson effect under the irradiation of radio frequency wave of 12 GHz. More than 20th Shapiro steps were observed and those step heights were oscillated according to the irradiation power. These characteristics were stable and reproducible for different configuration of junction area