Characterization of a Hole-Patterned Microstrip Superconducting Single-Photon Detector

Superconducting microstrip single-photon detectors (SMSPDs) with near-infrared sensitivity have significant advantages in terms of high quantum efficiency and low dark counts in a large active area. Hole-patterned superconductor microstrips have been reported for fast and efficient single-photon detection. In this work, we fabricated and characterized hole-patterned microstrips with different hole diameters on 5 nm thick MoSi films and an area of 500 x 500 mu m(2). We observed that the count rate curves of detectors 2 and 3 with holes tend to saturate slightly, whereas those of detector 1 without holes do not. Furthermore, the dark count is similar between detector 1 without holes and detector 2 with small holes and much lower than that of detector 3 with large holes. These experiments indicate that a proper hole is beneficial for efficiency without increasing the dark count rate.