Toward 1000-Pixel Superconducting-Tunnel-Junction Detectors for X-Ray Absorption Fine Structure Spectroscopy

Abstract

Superconducting tunnel junction (STJ) detectors have excellent energy resolution, high detection efficiency, and high counting rate in the soft X-ray energy range. These properties are suitable for synchrotron radiation facilities. However, in order to achieve a high throughput analysis for dopants with a lower concentration, the pixel number of STJ array detectors should be further increased to enlarge the sensitive area. As a first step, we have fabricated 400-pixel STJ array detectors and checked the operation yield and the uniformity of leakage current (\(I_{leak}\)) values. Fabricated STJs showed excellent current-voltage curves having low subgap current. The operation yield of STJs with \(I_{leak}\) values of less than 10 nA was 96 \(\%\). The average \(I_{leak}\) of 3.6 nA is roughly equivalent to that of the 100-pixel STJ array detector, which is open to users at synchroton radiation beam lines and have 12 eV energy resolution at 400 eV.