Abstract
The layer structure of a Nb/Al-based superconducting tunnel junction (STJ) X-ray detector was modified to improve the energy resolution (\(\Delta E\)) of STJ X-ray detectors by suppressing the recombination of excited quasiparticles in the electrodes. A 100-pixel array of 100 \(\times \) 100 \(\upmu \)m STJs with a symmetric layer structure of Nb (300 nm)/Al-AlO\(_{x}\)(70 nm)/Al (70 nm)/Nb (300 nm) was fabricated. Fabrication yields of the 100 pixels were more than 90 %. The average leak current of the STJ array was 8 nA. The mean \(\Delta E\) of the STJ array was 6.7 \(\pm \) 1.0 eV for 400 eV X-rays. This \(\Delta E\) is the best value reported for Nb/Al STJs.
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References
M. Ukibe et al., Jpn. J. Appl. Phys. 51, 010115-1–0110115-5 (2012). doi:10.1143/JJAP.51.010115
P. Fons et al., Phys. Rev. Lett. 96, 045504-1–045504-4 (2006). doi:10.1103/PhysRevLett.96.045504
S. Friedrich et al., Synch. Rad. News 27, 28–29 (2014). doi:10.1080/08940886.2014.930807
M. Ukibe et al., Chin. Phys. 24, 093301-1–093301-5 (2015). doi:10.1088/1674-1056/24/9/093301
M. Ohkubo et al., Sci. Rep. 2, 831-1–831-5 (2012). doi:10.1038/srep00831
M. Ukibe et al., Nucl. Instr. Meth. A 402, 95–103 (1998). doi:10.1016/S0168-9002(97)01060-7
Web site: https://unit.aist.go.jp/riif/openi/cravity/en/index.html
M. Ukibe et al., X-ray Spectr. 36, 260–263 (2007). doi:10.1002/xrs.967
S. Shiki et al., J. Low Temp. Phys. 167, 748–753 (2012). doi:10.1007/s10909-012-0526-6
D.J. Goldie et al., Appl. Phys. Lett. 64, 3169–3171 (1994). doi:10.1063/1.111328
D.M. Schlosser et al., Nucl. Instr. Meth. A 624, 270–276 (2010). doi:10.1016/j.nima.2010.04.038
Acknowledgments
This work was supported by JSPS KAKENHI Grant Number 15H03599. This work was performed under the approval of the Photon Factory Program Advisory Committee (Proposal No. 2013G642).
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Ukibe, M., Fujii, G., Shiki, S. et al. Modification of Layer Structures of Superconducting Tunnel Junctions to Improve X-ray Energy Resolution. J Low Temp Phys 184, 200–205 (2016). https://doi.org/10.1007/s10909-016-1488-x
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DOI: https://doi.org/10.1007/s10909-016-1488-x