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

Abstract

Epitaxial Ba_1−xSr_xTiO₃(BST)/YBa₂Cu₃O_7−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 Ba_1−xSr_xTiO₃ layers were epitaxially deposited on epitaxial (001) YBa₂Cu₃O_7−x layers. The leakage current density through the Ba_1−xSr_xTiO₃ 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 Ba_1−xSr_xTiO₃ 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 Ba_0.75Sr_0.25TiO₃ and Ba_0.8Sr_0.2TiO₃. The structural and electrical properties of the Ba_1−xSr_xTiO₃/YBa₂Cu₃O_7−x heterostructure indicated that conductive oxide materials with close lattice to...