ナノスケールでの元素分析に向けた 大規模超伝導トンネル接合アレイX 線検出器の開発

抄録

Superconducting-tunnel-junction (STJ) array X-ray detectors can exhibit excellent performance with respect to energy resolution, detection efficiency, and counting rate in a soft X-ray energy range. The detection area of STJ array detectors for high throughput analysis should be enlarged up to more than 10 mm² by increasing the pixel number of the arrays. In this work, in order to realize a STJ array with a large number of pixels up to 1000 within a 10-mm-square chip, we successfully fabricated STJ arrays arranging STJ pixels at high density. For the arrays, a wiring layer is embedded in a SiO₂ isolation layer underneath the STJ pixels. A STJ array detector with 100 pixels has an operation yield of 93% and a mean energy resolution of 12.5 +/- 0.7 eV in full-width at half-maximum for a C-Kα X-ray. The 12.5 eV is close to the natural line width of C in matrices, which means that the intrinsic energy resolution is a few eV. The detection performance was almost the same as those of conventional 100-pixel STJ array detectors. In addition, we developed an energy-dispersive X-ray spectroscopy analyzer combined with a scanning electron microscope (SEM) and the STJ array X-ray detector to realize nano-scale elemental mapping with high energy-resolving power. The analyzer simultaneously exhibits a high throughput of silicon drift detectors and a high energy resolution of wavelength-dispersive X-ray spectrometers.