SrTiO₃/YBa₂Cu₃O_7-δ bilayers: fabrication and characterization

We report on the deposition and characterization of SrTiO3/YBa2Cu3O7-δ bilayers with SrTiO3 thickness up to 0.7 μm. The films were grown by laser ablation onto NdGaO3 and also onto Nb-doped SrTiO3 substrates. Investigations by X-ray diffraction revealed very good crystallinity and (100) orientation of the SrTiO3 films. The relative permittivity was found to increase from 320 at room temperature to 780 at 65 K. The dielectric breakdown of a 4500 Å thick SrTiO3 film at 4.2 K occurred asymmetrically at 6.2×104V/cm and 2.2×105V/cm. The highly oriented YBa2Cu3O7-δ films deposited on top of these insulating layers had Tc(R=0) > 90 K and Jc(77 K)≳2.7×106 A/cm2. © 1992.