Takayuki Ishibashi

Bi2Sr2Can−1CunOy thin films by growth interruption technique

Abstract Bi 2 Sr 2 Ca n −1 Cu n O y (2212 and 2223 phases) thin films have been prepared on tilted SrTiO 3 (001) substrates by molecular beam epitaxy (MBE) with growth interruption technique, which is an advantageous method to enhance the surface diffusion of adatoms. Reflection high-energy electron diffraction (RHEED) observations have indicated that highly growth-controlled films can be obtained without precipitation of any impurity phases. Furthermore, RHEED intensity variations have indicated that the MBE growth may proceed by step-flow mode or two-dimensional (2D) island mode depending on the growth conditions. Atomic force microscopy (AFM) measurements have shown that the surfaces are single-step structures with step height of half a unit cell for the 2D island growth.

Josephson transport and crystallographic properties of Bi2Sr2CaCu2Oy junctions on (100) MgO bicrystal substrates

Abstract We report the Josephson effects of the grain boundary Bi 2 Sr 2 CaCu 2 O y (2212) bicrystal junctions formed on (100)MgO bicrystal substrates with a misorientation angle of 24° by in situ coevaporation growth technique using molecular beam epitaxy (MBE). It is found that the 2212 film on MgO bicrystal substrate consists of the a − b twin structures by reflection high-energy electron diffraction (RHEED) observation. The atomic force microscope (AFM) observation at the 2212 bicrystal junction interface suggests that the actual junction boundary strongly deviates from the straight line geometry. These microscopic geometry effects are discssed with the observed Josephson effects.

Surface diffusion in molecular beam epitaxy of Bi/sub 2/Sr/sub 2/Ca/sub n-1/Cu/sub n/O/sub x/

Thin films of Bi/sub 2/Sr/sub 2/CuO/sub 6+x/ (2201) phase have been tilted SrTiO/sub 3/ [001] substrates by co-deposition method, and Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+x/ (2212) phase by interruption technique. The surface diffusion characteristics the molecular beam epitaxy (MBE) of both phases have also been investigated by using in-situ reflection high energy electron diffraction (RHEED). The periodic RHEED intensity oscillations and recovery process been analyzed for 2201 and 2212 phases.<<ETX>>