Development of embedded STJ for large format array X-ray detector

Abstract

Abstract We have been developing an embedded superconducting tunnel junction (e-STJ) for a large-format array X-ray detector. Compared with the conventional STJ array, the e-STJ array is suitable for enlarging the detection area effectively because the e-STJ detector utilizes a three-dimensional packaging technology. To investigate the relationship between the fabrication method and the electric characteristics of the e-STJ, we designed and fabricated three types of simplified e-STJ and measured their subgap leakage current in the temperature range from 4.2 K to 0.3 K. We found that the roughness of the embedding hole on the Si substrate and the contact part between the embedded STJ and the side of the embedding hole affected the subgap leakage current.