Regions with reduced energy gap induced by the proximity effect give rise to quasi-particle loss in Josephson-junction X-ray detectors, but may also be used advantageously for quasi-particle collection. The influence of the thickness of the Al proximity layers in Nb/Al1 , AlOx, Al2/Nb Josephson tunnel junctions on the electrical characteristics has been investigated theoretically and experimentally. Theoretically it is found that the strength of the proximity effect is mainly determined by the proximity effect is mainly determined by the proximity parameters γM1 (γM2) of the electrodes. Good fits of the measured I-V curves with theory were obtained for junctions with thicknesses dA11 ranging from 4 to 25 nm and dA12=3 nm, with γM2≈0.12 and γM1/γM2=dA11/d A12. For all junctions the proximity knee remains more pronounced than predicted.
|Number of pages||2|
|Journal||IEEE transactions on applied superconductivity|
|Publication status||Published - 1993|
|Event||1992 Applied Superconductivity Conference, ASC 1992 - Chicago, United States|
Duration: 23 Aug 1992 → 28 Aug 1992