Fabrication of NbTiN Josephson Junctions With Thermally Oxidized Hf Tunnel Barriers
Fabrication of NbTiN Josephson Junctions With Thermally Oxidized Hf Tunnel Barriers
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DOI：
10.1109/tasc.2019.2906278
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发表时间：
2019-08
影响因子：
1.8
通讯作者：
H. Akaike;K. Munemoto;Yoshito Sakakibara;A. Fujimaki
中科院分区：
文献类型：
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作者：
H. Akaike;K. Munemoto;Yoshito Sakakibara;A. Fujimaki
在热氧化硅衬底上制备了具有HfOx势垒的NbTiN约瑟夫森结(JJ)。HfOx阻挡层采用不同电阻率的Hf覆盖层。低电阻率的Hf覆盖层产生了具有高质量参数的结。通过改变Hf层的热氧化条件，获得了在0.01-0.4kA/cm2范围内的临界电流密度Jc。对于100个JJ中的85个，临界电流均匀度估计为从最大到最小的扩散±10.1%。我们评估了JC的比容，约为110ff/μm2，范围从0.1kA/cm2到0.4kA/cm2。用NbN电极代替NbTiN电极，改善了准粒子隧道特性。
We fabricated NbTiN Josephson junctions (JJs) with HfOx barriers on thermally oxidized Si substrates. Hf overlayers with different resistivities were used for the HfOx barrier formation. The Hf overlayer with low resistivity produced junctions with high quality parameters. The critical current density (Jc) was obtained in the range of 0.01–0.4 kA/cm2 by changing the thermal oxidation conditions of the Hf layer. The critical current uniformity was estimated at a maximum-to-minimum spread of ±10.1% for 85 of the 100 JJs. We evaluated the specific capacitance, which was approximately 110 fF/μm2 for the Jc ranging from 0.1 to 0.4 kA/cm2. The quasiparticle tunnel characteristics were improved by using the NbN electrodes instead of the NbTiN electrodes.