Development of Superconducting Tunnel Junction X-ray Detector with High Absorption Yields Utilizing Silicon Pixel Absorbers

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 m 100 m and are composed of Nb-Al/AlO/Al-Nb thin layers. The SPAs are also 100 m 100 m and have a depth of 400 m, and are isolated from each other by a deep trench with a depth of 350 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 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.