Fabrication of High-Tc Superconducting Co-planar Josephson Junctions Using Focused Ion Beam

利用聚焦离子束(FIB)制备了YBaCuO共面结。YBaCuO具有超流的二维电导率。在YBaCuO结中，共面结具有最有效的电流流动。我们已经用FIB制作了两种类型的共面结(一种是冷损伤衬底类型)。另一种是局部离子辐照)。利用聚焦离子束制备了YBaCuO与反常生长的YBaCuO共面约瑟夫森结。利用FIB在MgO(100)衬底上形成一个窄的离子损伤区域，通过改变YBaCuO薄膜的厚度来制备结。结具有厚度依赖的特性。从结面观察，随着薄膜厚度的增加，YBaCuO在较薄的薄膜结中水平生长，结长减小。用Be离子辐照YBaCuO薄膜制备了约瑟夫森结.结具有RSJ的I-V曲线，IcRn乘积从0.6 mV到2.0 mV，在4.2K有良好的磁响应.结的临界电流密度随离子注量的增加呈指数下降.从损伤分布的估计来看，结长度随着离子注量的增加而增加。损伤后的YBaCuO薄膜表现出正常金属的特性。因此，我们认为这些结是具有邻近效应的SnS型结。当测量六个月前制作的结时，结的电流分布没有改变。结的稳定性良好。

YBaCuOco-planar junctions were fabricated using Focused Ion Beam (FIB) . A YBaCuO has two-dimentional conductivity of super-current. The co-planar junction has the most effective current flow in the YBaCuO Junctions. We have been fabricated two types of the co-planar junctions using FIB (One is the colally damaged substrate type. The other is the locally ion irradiate type) .YBaCuO co-planar Josephson junctions with the abnormally grown YBaCuO were produed using Focused Ion Beam. FIB was used to form a narrow region of ion damage on the MgO (100) substrate.The junctions were fabricated by changing the thickness of a YBaCuO thin film. The junctions had the thickness dependence of the characterstics. From the observation of the junction surface, the junction length was decreased with increasing film thickness by the horizontal growth of the normally grown YBaCuO in the thinner film junctions. It is considered that the Jeosephson current for the thicker film junctions flows dominantly in the microshorts, and Josephson current for the thinner film junctions flows in the abnormally grown YBaCuO area.Josephson junctions were fabricated by irradiating Be ions on a YBaCuO thin film with FIB.The junctions had the I-V curve of RSJ,the IcRn product from 0.6mV to 2.0mV,and a good magnetic response at 4.2K.The critical current density of the junctions decreased exponentially with increasing the ion fluence. From the estimation of the damage distrubution, the junction length increased with the ion fluence. The damaged YBaCuO thin film showed the characteristic of the normal metal. Therefore, it is considered that the junctions had the SNS type junction with a proximity effect. When the junctions which were fabricated six mounth ago were measured, the current distribution of the junction did not changed. The junction stability was good.