PT Journal
AU Baeva, EM
   Sidorova, MV
   Korneev, AA
   Smirnov, KV
   Divochy, AV
   Morozov, PV
   Zolotov, PI
   Vakhtomin, YB
   Semenov, AV
   Klapwijk, TM
   Khrapai, VS
   Goltsman, GN
TI Thermal properties of NbN single-photon detectors
SO Phys. Rev. Applied
JI Phys. Rev. Applied
PY 2018
BP 064063 (1 to 8)
VL 10
IS 6
DI 10.1103/PhysRevApplied.10.064063
DE NbN SSPD; SNSPD
AB We investigate thermal properties of a NbN single-photon detector capable of unit internal detection efficiency. Using an independent calibration of the coupling losses, we determine the absolute optical power absorbed by the NbN film and, via resistive superconductor thermometry, the temperature dependence of the thermal resistance Z(T) of the NbN film. In principle, this approach permits simultaneous measurement of the electron-phonon and phonon-escape contributions to the energy relaxation, which in our case is ambiguous because of the similar temperature dependencies. We analyze Z(T) with a two-temperature model and impose an upper bound on the ratio of electron and phonon heat capacities in NbN, which is surprisingly close to a recent theoretical lower bound for the same quantity in similar devices.
ER