Intrinsic Josephson Junctions in Bi-2212 Thin Films Fabricated by Metal-Organic Decomposition

We fabricated a mesa 10 μm × 10 μm in area and ~ 150 nm in height on a single grain in a 240-nm Bi₂Sr₂CaCu₂O_8+δ/MgO thin-film grown by metal-organic decomposition (MOD) with face-to-face annealing. A multi-branch structure peculiar to intrinsic Josephson junctions (IJJs) was observed in the I-V characteristics of the fabricated mesa, and this structure was characterized by approximately 100 quasiparticle branches with critical current densities of 1 kA/cm² and voltage-jump intervals of 20 mV. Moreover, the temperature dependence of the critical current was in good agreement with a theoretical result based on c-axis Josephson tunneling in d-wave superconductors. These results imply that the thin films grown by MOD have sufficient quality to fabricate IJJs for practical terahertz applications.