EFFECTS OF THE LATTICE MISMATCH AND VICINAL POLISHING ON THE HETEROEPITAXIAL GROWTH OF BI2SR2CUOX BUFFER LAYERS ON MGO (100) FOR BI-SR-CA-CU-O FILMS

Epitaxial Bi2Sr2CuOx films oriented with the c-axis normal to the substrate surface were fabricated on MgO (100) single crystal substrates by using a reactive evaporation method. An in-situ reflection high energy electron diffraction observation has revealed that the strain of a Bi2Sr2CuOx film caused by the lattice mismatch between Bi2Sr2CuOx and MgO remained until the thickness of the films reaches 250 angstrom. It has also become clear by using vicinally polished MgO (100) substrates that the orientation of the c-axis of the Bi2Sr2CuOx film was obstructed by the deviation from the (100) plane of the MgO surface until a thickness of 300 angstrom. A Bi2Sr2CuOx buffer layer with a thickness of 300 angstrom is recommended on an MgO (100) single crystal substrate when fabricating superconducting Bi-Sr-Ca-Cu-O films.