Heteroepitaxial growth of Ba1−xSrxTiO3/YBa2Cu3O7−x by plasma-enhanced metalorganic chemical vapor deposition

Abstract

Epitaxial Ba1−xSrxTiO3(BST)/YBa2Cu3O7−x heterostructures with superior electrical and dielectric properties have been fabricated by plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD). Data of x-ray diffraction and high resolution transmission electron microscopy showed that 〈100〉 oriented Ba1−xSrxTiO3 layers were epitaxially deposited 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 2×105 V/cm) operation. Moreover, the results of capacitance-temperature measurements showed that the PE-MOCVD Ba1−xSrxTiO3 films had Curie temperatures of about 30 °C and a peak dielectric constant of 600 at zero bias voltage. The Rutherford backscattering spectrometry and 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/YBa2Cu3O7−x heterostructure indicated that conductive oxide materials with close lattice to Ba1−xSrxTiO3 can be good candidates for the bottom electrode.