HIGH T-C STEP-EDGE JOSEPHSON-JUNCTIONS ON SILICON SUBSTRATES

The epitaxial buffer system CeO2/YSZ was used to prepare YBCO films of high crystalline quality on silicon substrates by laser deposition. A n advanced technique of step preparation in the YSZ buffer layer prese rved the critical current densities of j(C) (77 K)similar to 10(6) A/c m(2) for 30 nm thick YBCO films also in the etched parts of the substr ate. Further, a homogeneous growth over the 35 to 45 nm deep steps was observed. So we were able to realize step-edge Josephson junctions wi th critical temperatures up to 77 K. Our dc SQUIDs on silicon substrat es showed voltage modulation 74 K. (C) 1995 American Institute of Phys ics.