Fabrication of large array of superconducting-tunnel-junction detectors for mass spectrometry

Superconducting tunnel junction (STJ) detectors have a fast time response and a low threshold to detect such quanta as phonons. These characteristics are advantageous to their applications in mass spectrometry for large molecules. However, one drawback is small active area, which cancels out the high quantum efficiency for large molecules. In this study, therefore, arrays of 100 niobium-based proximized STJ elements with a size of 200×200 μm2 have been fabricated to improve effective detection area to achieve a practical short measurement time.