IMPEDANCE CONTROL OF TL2BA2CACU2OX JOSEPHSON-JUNCTIONS ON MGO SUBSTRATES FOR MILLIMETER-WAVE SENSING

SIS - type (Superconductor - Insulator - Superconductor) intrinsic sta cked Josephson junctions (ISJJs) and SNS - type (Superconductor - Norm al conductor - Superconductor) step-edge Josephson junctions (SEJJs) h ave been successfully fabricated using anisotropic TI2Ba2CaC2Ox thin f ilms on MgO substrates, In order to apply them to millimeter wave rece ivers, their normal resistance (Rn) was controlled, which determines t he impedance matching for millimeter wave signals. For electrical tran sport along the c-axis, the Rn of a single unit ISJJ with a 5 mu m-squ are mesa was estimated to be 580 Omega, For electrical transport paral lel to the ab-plane, the R-n of series connected six SEJJs (6-SEJJs) w ith the gentle slope of 28 degrees was 2.0 to 3.8 Omega. Since their r esponsivities as millimeter wave detectors were two to three orders of magnitude larger than those of single SEJJs, efficient IF (intermedia te frequency) output of fundamental mixing with LO (local oscillation) power of a few microwatts was observed up to 95 K.