Large sensitive-area NbN nanowire superconducting single-photon detectors fabricated on single-crystal MgO substrates

Abstract

We report on the performance of large area NbN nanowiresuperconducting single-photon detectors (SSPDs). 20 × 20 μ m 2 area SSPDs with 80 and 100 nm linewidths and 50% fill factor were fabricated in 4 - nm -thick NbN filmsgrown on single-crystal MgO substrates. The high quality of the devices was verified by electrical and optical testing and compares favorably to measurements of 10 × 10 μ m 2 area SSPDs. Measurements of kinetic inductance versus bias current indicate that the constriction density is low. The fiber-coupled detection efficiency of the devices was 0.4%–3.5% at 100 Hz dark count rate.