PT Journal
AU Zolotov, PI
   Semenov, AV
   Divochiy, AV
   Goltsman, GN
   Romanov, NR
   Klapwijk, TM
TI Dependence of photon detection efficiency on normal-state sheet resistance in marginally superconducting films of NbN
SO IEEE Trans. Appl. Supercond.
JI IEEE Trans. Appl. Supercond.
PY 2021
BP 1
EP 5
VL 31
IS 5
DI 10.1109/TASC.2021.3061923
DE NbN SSPD; SNSPD
AB We present an extensive set of data on nanowire-type superconducting single-photon detectors based on niobium-nitride (NbN) to establish the empirical correlation between performance and the normal-state resistance per square. We focus, in particular, on the bias current, compared to the expected depairing current, needed to achieve a near-unity detection efficiency for photon detection. The data are discussed within the context of a model in which the photon energy triggers the movement of vortices i.e. superconducting dissipation, followed by thermal runaway. Since the model is based on the non-equilibrium theory for conventional superconductors deviations may occur, because the efficient regime is found when NbN acts as a marginal superconductor in which long-range phase coherence is frustrated.
ER