MICROSTRUCTURAL STUDY OF YBA2CU3O7 SRTIO3/YBA2CU3O7 HETEROEPITAXIAL TRILAYER FILMS GROWN ON (100) SRTIO3 SUBSTRATES/

Detailed transmission electron microscopic study has been carried out on heteroepitaxial YBa2Cu3O7/SrTiO3/YBa2Cu3O7 trilayer thin films grow n on (100)SrTiO3 substrates prepared by DC and RF magnetron sputtering . The microstructural results showed the existence of some a-axis-orie nted YBCO grains 20-90 nm wide in the c-axis-oriented YBCO matrix. Som e of the a-axis grains in the lower YBCO thin film layer have protrude d into the above SrTiO3 layer, which may cause short circuit between t he two YBCO superconducting layers. This is unsuitable for the applica tion of trilayer thin films for microelectronic devices. The defects o n the surface of the substrates would also influence the growth qualit y of the YBCO thin films.