Ferroelectric bismuth titanate/superconductor (Y-Ba-Cu-O) thin-film heterostructures on silicon

The growth by pulsed-laser deposition of c-axis-oriented bismuth titanate (BTO)/YBa2Cu3O7(YBCO) superconductor heterostructures on [001]-oriented Si with epitaxial yttria-stabilized ZrO2 as a buffer layer is reported. X-ray-diffraction studies of the heterostructures show that all the layers grow in the c-axis orientation, with a rocking angle of 1.0°–1.2° for the bismuth titanate layer and 0.6°–0.8° for the YBCO layer. Rutherford backscattering ion channeling yields of 28% at the surface have been obtained. Transmission electron microscopy of cross-sectioned samples reveal that the BTO layer has a significant density of translational boundaries that propagate at 45° to the film surface. The BTO film exhibits ferroelectric hysteresis and a dielectric constant in the range of 180–200.