INSITU EPITAXIAL-GROWTH OF BI-SR-CA-CU-O FILMS AND SUPERLATTICES BY MBE USING AN OXYGEN RADICAL BEAM

Epitaxial Bi-Sr-Ca-Cu-O thin films and superlattices have been grown on MgO (100) and SrTiO3 (100) substrates by the MBE technique using an oxygen radical beam produced by RF excitation. During the first deposition of Ca atomic layers on MgO, the epitaxial direction was found rotated by 45-degrees between Ca-free and Ca-containing phases. Superlattices of Bi2Sr2CaCu2O8 (2212)/Bi2Sr2CuO6 (2201), in which 2212 layers with a thickness of m c-axis half unit cells are separated by nonsuperconducting 2201 layers of n half unit cells, were grown by this technique. We found that the superlattices exhibit similar superconductivity independent of both the m and n half-unit-cell numbers, indicating the two dimensionality of this superconductor.