JOSEPHSON PROPERTIES OF BI2SR2CACU2OY BICRYSTAL JUNCTIONS GROWN BY A SEQUENTIAL DEPOSITION TECHNIQUE USING MOLECULAR-BEAM EPITAXY

We report Josephson and crystallographic properties of the Bi2Sr2CaCu2 Oy junctions fabricated on MgO(100) bicrystal substrates by a molecula r-beam-epitaxy method incorporating co-evaporation and sequential depo sition techniques. With the sequential deposition technique which has the advantage of promoting the surface diffusion of adatoms, we obtain ed the highly growth-controlled films without precipitation of any sec ond impurity phases. During the film growth, the sharp reflection high -energy electro diffraction (RHEED) patterns were also observed. Howev er, the RHEED patterns showed the a-b twin structures due to the latti ce mismatch, which influenced the Josephson transport properties at th e junction boundary. The normal resistance of the bicrystal junction w as 1.5 Omega and the IcRn product was 0.75 mV at 4.2 K. The Shapiro st eps under millimeter-wave irradiation were clearly observed up to 65 K . We also irradiation were clearly observed up to 65 K. We also observ ed the Josephson microwave self-radiation spectra at receiving frequen cy f(REC)=22 GHz. The observed Josephson transport properties are disc ussed in relation to the microscopic crystallographic properties.