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Superconducting-tunnel-junction (STJ) array X-ray detectors have exhibited excellent characteristics for fluorescence-yield X-ray absorption fine structure (XAFS) in a soft X-ray range. For high-throughput XAFS analyses, we developed a new close-packed STJ arrangement with a space of 10 $$\upmu $$ m (use the correct space) between adjacent STJ pixels by using three-dimensional multilayer structure (3D-STJ) with the wiring layer underneath the STJ pixel layer. In this work, in order to solve a double-peak response originating from absorption events in the top and bottom electrodes, we have fabricated the 3D-STJ with an asymmetric layer structure. Single-peak response for the soft X-rays below 0.7 keV was obtained. The closed-packed 3D-STJ array detector with 100 pixels has an operation yield of 93 % and a mean energy resolution of 12.5 $$\pm $$ 0.7 eV in full-width at half-maximum for the C-K $$\alpha $$ X-ray. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A superconducting tunnel junction (STJ) array detector along with silicon pixel absorbers (STJ-SPA) is fabricated to achieve high detection efficiency at X-ray energies below 10 keV. The STJ pixels have dimensions of 100 $$\upmu $$ m $$\times $$ 100 $$\upmu $$ m and are composed of Nb-Al/AlO $$_{X}$$ /Al-Nb thin layers. The SPAs are also 100 $$\upmu $$ m $$\times $$ 100 $$\upmu $$ m and have a depth of 400 $$\upmu $$ m, and are isolated from each other by a deep trench with a depth of 350 $$\upmu $$ m. The detection efficiency of the STJ-SPA exceeds 95 % at X-ray energies below 10 keV, and its energy resolution is 82 eV FWHM, as measured at the Si K $$\upalpha $$ line at 1740 eV. By means of the STJ-SPA detector, the X-ray absorption spectrum of the light element sulfur with a concentration of less than 0.1 wt% in a soda-lime glass sample was successfully acquired. [ABSTRACT FROM AUTHOR]