HETEROEPITAXIAL GROWTH OF BA1-XSRXTIO3 YBA2CU3O7-X BY PLASMA-ENHANCEDMETALORGANIC CHEMICAL-VAPOR-DEPOSITION

Epitaxial Ba1-xSrTiO3(BST)/YBa2Cu3O7-x, heterostructures with superior electrical and dielectric properties have been fabricated by plasma-e nhanced metalorganic chemical vapor deposition (PE-MOCVD). Data of x-r ay diffraction and high resolution transmission electron microscopy sh owed that [100] oriented Ba1-xSrxTiO3 layers were epitaxially deposite d on epitaxial (001) YBa2Cu3O7-x, layers. The leakage current density through the Ba1-xSrxTiO3 films was about 10(-7) A/cm2 at 2 V (about 2 X 10(5) V/cm) operation. Moreover, the results of capacitance-temperat ure measurements showed that the PE-MOCVD Ba1-xSrxTiO3 films had Curie temperatures of about 30-degrees-C and a peak dielectric constant of 600 at zero bias voltage. The Rutherford backscattering spectrometry a nd x-ray diffraction results showed that the BST film composition was controlled between Ba0.75Sr0.25TiO3 and Ba0.8Sr0.2TiO3. The structural and electrical properties of the Ba1-xSrxTiO3/YBa2CuO7-x heterostruct ure indicated that conductive oxide materials with close lattice to Ba 1-xSrxTiO3 can be good candidates for the bottom electrode.