Unusual I/V characteristics of Nb/Al/AlOx/Al/AlOx/Nb SINIS tunnel junctions

被引:1
作者
Nevirkovets, IP [1 ]
Ketterson, JB [1 ]
Rowell, JM [1 ]
机构
[1] Northwestern Univ, Dept Phys & Astron, Evanston, IL 60208 USA
来源
SUPERCONDUCTING AND RELATED OXIDES: PHYSICS AND NANOENGINEERING IV | 2000年 / 4058卷
关键词
Josephson effect; double-barrier junctions; subgap structure; coherent tunneling;
D O I
10.1117/12.397836
中图分类号
TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
Double-barrier Nb/Al-AlOx-Al-AlOx-(Al/)Nb devices with various thickness and purity of the middle Al layer were fabricated and investigated. It is found that the subgap structure that appears in the current voltage characteristics is very sensitive to the parameters of the middle film. In addition to the formerly reported gap-difference structure, we observed its half-voltage "subharmonic" and a novel magnetic-field-sensitive structure that develops at a voltage V approximate to Delta (Nb)/e (Delta (Nb) is the superconducting energy gap of Nb). In general, the devices with a cleaner Al electrode reveal better reproducibility of their characteristics, whereas the devices with "impure" Al (deposited in presence of a small amount of oxygen added to the Ar) tend to have more complicated and difficult to reproduce subgap structure. In addition, an anomalously large Josephson critical current was observed for devices with a small thickness of the middle Al layer.
引用
收藏
页码:212 / 219
页数:8
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