High quality Nb/Al‐AlOx/Nb Josephson junction
High quality Nb/Al‐AlOx/Nb Josephson junction
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高品质 Nb/Al-AlOx/Nb 约瑟夫森结
DOI：
10.1063/1.95696
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发表时间：
1985
影响因子：
4
通讯作者：
H. Hayakawa
中科院分区：
文献类型：
--
作者：
S. Morohashi;F. Shinoki;A. Shoji;M. Aoyagi;H. Hayakawa
我们改进了Nb/Al-AlOx/Nb约瑟夫森结的质量，并获得了所有难熔约瑟夫森结最优异的结特性。当临界电流密度ij=500A/cm2时，Vm值(临界电流与亚隙电阻的乘积)为88 mV，当ij=1000A/cm2时，Vm值为72 mV。在Ij为2400A/cm2时，Vm值大于40 mV。在约瑟夫森电路中，较高的Vm值对于获得低子间隙泄漏电流而不是降低到负载的转移电流是很重要的。这些特性是通过提高Nb薄膜的质量和优化Al厚度来实现的。我们还证实了Ij可以在40-4600A/cm2的范围内由氧化压力和时间控制。
We have improved the quality of Nb/Al‐AlOx/Nb Josephson junctions and obtained the most excellent junction characteristics ever obtained for all refractory Josephson junctions. The Vm values (the product of the critical current and the subgap resistance measured at 2 mV) are 88 mV at the critical current density Ij =500 A/cm2 and 72 mV at Ij =1000 A/cm2. The Vm values are larger than 40 mV up to Ij of 2400 A/cm2. The high Vm values are important to obtain the low subgap leakage current and not to reduce the transfer current to the load in Josephson circuit. These characteristics have been achieved by improving the quality of the Nb film and optimizing the Al thickness. We have also confirmed that Ij can be controlled by both the oxidation pressure and time in the range of 40–4600 A/cm2.