Electrical interface structure in YBa/sub 2/Cu/sub 3/O/sub 7-x//metal contact

We have investigated the electrical contacts between YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) and Au. The dI/dV characteristics of the c-axis-oriented YBCO/Au/Nb junctions reveal the existence of a tunnel barrier at the YBCO/Au interface. The experimental results of the YBCO/LaGaO/sub 3//Au/Nb junction suggest p-type degenerate semiconductor-like behavior of YBCO along the c-axis direction. The anomalously small I/sub c/R/sub n/ of a few /spl mu/V in the c-axis direction are interpreted as the band bending at the YBCO surface. On the other hand, the experimental I/sub c/R/sub n/ value of 120 /spl mu/V in the a-axis-oriented YBCO/Au/Nb junction is understood within the scope of conventional theory.<
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