PREPARATION, CHARACTERIZATION AND DIELECTRIC-PROPERTIES OF YBA2CU3O7-DELTA INSULATOR-HETEROSTRUCTURES/

YBa2Cu3O7-delta/insulator/Au-heterostructure on SrTiO3 or LaAlO3 subst rates were prepared to study the properties of the materials SrTiO3, B aTiO3 and CeO2. X-ray diffraction measurements in Bragg-Brentano geome try show c-axis-oriented growth for the superconductor and the insulat ors SrTiO3 and CeO2. Typical values for the rocking curve width of the different insulating films are between 0.4 degrees and 0.8 degrees. T he highest breakdown fields are measured for the insulator SrTiO3 with +37.5 kV/mm and -8.8 kV/mm. The permittivity for CeO2 is independent of applied field and only weakly temperature dependent. This is in con trast to the perovskite type insulators, where the permittivity depend s on temperature and field. The measured real- and imaginary- parts of the dielectric constant differ as a function of frequency (20 Hz - 1 MHz) from the bulk-materials for all three insulators. This behaviour can be explained with a resistance in series and a conductance paralle l to the capacitance.