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-degrees-1.2-degrees for the bismuth titanate layer and 0.6-degrees-0.8-degrees 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-degrees to the film surface. The BTO film exhibits ferroelectric hysteresis and a dielectric constant in the range of 180-200.