FABRICATION AND CHARACTERIZATION OF YBA2CU3O7-X THIN-FILM STEP JUNCTIONS ON MGO SUBSTRATES

We have investigated the tunneling properties of proximity-effect supe rconductor-normal-superconductor junctions based on high-temperature s uperconductor YBCO thin films and normal Ag layer. The systematic anal ysis of the properties of the films and the fabrication process which leads to a good-quality junctions is discussed in detail. The properti es of the tunneling barrier are investigated by de and rf measurements : the de properties reveal that our junctions fully behave as expected from the de Gennes model. Regular Shapiro steps in the current-voltag e characteristics are obtained as a result of microwave irradiation, i ndicating reliable rf properties of the junctions.