PT Journal
AU Semenov, AD
   Heusinger, MA
   Renk, KF
   Menschikov, E
   Sergeev, AV
   Elant'ev, AI
   Goghidze, IG
   Gol'tsman, GN
TI Influence of phonon trapping on the performance of NbN kinetic inductance detectors
SO IEEE Trans. Appl. Supercond.
JI IEEE Trans. Appl. Supercond.
PY 1997
BP 3083
EP 3086
VL 7
IS 2
DI 10.1109/77.621984
DE NbN KID
AB Voltage and microwave photoresponse of NbN thin films to modulated and pulsed optical radiation reveals, far below the superconducting transition, a response time consistent with the lifetime of nonequilibrium quasiparticles. We show that even in 5 nm thick films at 4.2 K the phonon trapping is significant resulting in a quasiparticle lifetime of a few nanoseconds that is an order of magnitude larger than the recombination time. Values and temperature dependence of the quasiparticle lifetime obey the Bardeen-Cooper-Schrieffer theory and are in quantitative agreement with the electron-phonon relaxation rate determined from the resistive response near the superconducting transition. We discuss a positive effect of the phonon trapping on the performance of kinetic inductance detectors.
ER