Properties of junctions using a-axis oriented Y-Ba-Cu-O films.

在一定条件下，采用直流偏压衬底支架射频磁控溅射，制备了YBa<@D22@>D2Cu<@D23@> d2o (YBCO)/SrTiO<@D23@>D2(STO)/Au和YBCO/PrGaO<@D23@>D2(PGO)/Au的夹心型SIN结。研究了不同势垒厚度结的差分电导-电压（dI/dV-V）曲线。该结表现出类似隧道的行为，尽管一些结表现出针孔短路曲线。结在曲线上的微分电导梯度变化约为(]SY.+-。() 20 mv。这种变化随着屏障厚度的减小而明显。另一方面，对于薄势垒的结，也观察到小的零偏异常。具有PGO屏障的连接点曲线与具有STO屏障的连接点曲线相似。认为隧穿发生在非均匀势垒中的薄区。然后，研究了dI/dV-V曲线对氧气热处理的影响。为了获得dI/dV- v曲线中dI/dV梯度的变化，最佳退火时间为2-4h。随着退火时间的延长，结本底电导的斜率变陡。

Sandwich type SIN junctions of YBa<@D22@>D2Cu<@D23@>D2Ox(YBCO)/SrTiO<@D23@>D2(STO)/Au and YBCO/PrGaO<@D23@>D2(PGO)/Au were fabricated using a-axis oriented YBCO films under the some conditions using a rf magnetron sputtering with dc voltage biased substrate holder. The differential conductance-voltage(dI/dV-V) curves of junctions with defferent barrier thickness were investigated. The junction showed the tunnel-like behavior, though some junctions showed the curves with pinhole-short-circuits. The junctions had the change in the gradient of differential conductance in the curves at about (]SY.+-。[) 20mV.This change was obviously observed with decreasing the barrier thickness. On the other hand, it was also observed the small zero bias anomalies for the junctions with thin barrier. The curves of junctions with PGO barrier were simillar to those with the STO barrier. It is considered that the tunneling occurs via thin region in the ununiform barrier.And then, the effects of dI/dV-V curves on the heat treatment in oxygen gas were also investigated. In order to obtain the change in the gradient of dI/dV in the dI/dV-V curve, the optimum annealing time was 2-4h. The slope of the background conductance of junctions becomes steep with increasing the annealing time.