Title :
YBCO artificial grain boundary junctions on Si
Author :
Chen, J. ; Yamashita, T. ; Suzuki, H. ; Myoren, H. ; Nakajima, K. ; Osaka, Y.
Author_Institution :
Tohoku Univ., Sendai, Japan
fDate :
3/1/1993 12:00:00 AM
Abstract :
Si bicrystal substrates with different misorientation angles were fabricated using the hot-press method and their qualities were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). YBa/sub 2/Cu/sub 3/O/sub 7- delta / (YBCO) epitaxial thin films were grown on such substrates by RF magnetron sputtering, with yttria and yttria-stabilized zirconia as the buffer layers. The properties of bridge-type junctions patterned on the film by an excimer laser were studied from 4.2 K to 77 K. It was found that the critical current density of the artificial grain boundary (AGB) junction (J/sub c//sup A/) was always less than that of the junction made on Si single-crystal grains (J/sub c//sup G/). The (J/sub c//sup A/)/(J/sub c//sup G/) ratio decreased exponentially as the misorientation angle ( theta ) was increased. The effect of temperature and microwave irradiation showed that the properties of AGB junctions with theta <5 degrees were limited by flux creep. In contrast, AGB junctions with theta >or=10 degrees showed the Josephson effect.<>
Keywords :
Josephson effect; X-ray diffraction examination of materials; barium compounds; critical current density (superconductivity); elemental semiconductors; flux creep; grain boundaries; high-frequency effects; high-temperature superconductors; scanning electron microscope examination of materials; silicon; sputtered coatings; transmission electron microscope examination of materials; yttrium compounds; 4.2 to 77 K; AGB junctions; Josephson effect; RF magnetron sputtering; RHEED; Rutherford backscattering; SEM; Si bicrystal substrates; TEM; X-ray diffraction; XRD; Y/sub 2/O/sub 3/ buffer layers; Y/sub 2/O/sub 3/-ZrO/sub 2/; YBa/sub 2/Cu/sub 3/O/sub 7- delta / epitaxial thin films; artificial grain boundary junctions; bridge-type junctions; critical current density; excimer laser; flux creep; hot-press method; microwave irradiation; misorientation angle; scanning electron microscopy; superconductor-semiconductor junction; temperature effect; transmission electron microscopy; Grain boundaries; Magnetic flux; Radio frequency; Scanning electron microscopy; Sputtering; Substrates; Transmission electron microscopy; X-ray diffraction; X-ray scattering; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
