PT Journal
AU Men’shchikov, EM
   Gogidze, IG
   Sergeev, AV
   Elant’ev, AI
   Kuminov, PB
   Gol’tsman, GN
   Gershenzon, EM
TI Superconducting fast detector based on the nonequilibrium inductance response of a film of niobium nitride
SO Tech. Phys. Lett.
JI Tech. Phys. Lett.
PY 1997
BP 486
EP 488
VL 23
IS 6
DI 10.1134/1.1261724
DE NbN KID
AB A new type of fast detector is proposed, whose operation is based on the variation of the kinetic inductance of a superconducting film caused by nonequilibrium quasiparticles created by the electromagnetic radiation. The speed of the detector is determined by the rate of multiplication of photo-excited quasiparticles, and is nearly independent of the temperature, being less than 1 ps for NbN. Models based on the Owen-Scalapino scheme give a good description of the experimentally determined dependence of the power-voltage sensitivity of the detector on the modulation frequency. The lifetime of the quasiparticles is determined, and it is shown that the reabsorption of nonequilibrium phonons by the condensate has a substantial effect even in ultrathin NbN films 5 nm thick, and results in the maximum possible quantum yield. A low concentration of equilibrium quasiparticles and a high quantum yield result in a detectivity D*=1012 W−1·Hz1/2 at a temperature T=4.2 K and D*=1016 W−1·cm· Hz1/2 at T=1.6 K.
ER