Niobium Superconducting Nanowire Single-Photon Detectors

Abstract

We investigate the performance of superconducting nanowire photon detectors\nfabricated from ultra-thin Nb. A direct comparison is made between these\ndetectors and similar nanowire detectors fabricated from NbN. We find that Nb\ndetectors are significantly more susceptible than NbN to thermal instability\n(latching) at high bias. We show that the devices can be stabilized by reducing\nthe input resistance of the readout. Nb detectors optimized in this way are\nshown to have approximately 2/3 the reset time of similar large-active-area NbN\ndetectors of the same geometry, with approximately 6% detection efficiency for\nsingle photons at 470 nm.\n