PT Unknown
AU Il'in, KS
   Gol'tsman, GN
   Voronov, BM
   Sobolewski, R
TI Characterization of the electron energy relaxation process in NbN hot-electron devices
SE Proc. 10[super:th] Int. Symp. Space Terahertz Technol.
PY 1999
BP 390
EP 397
DE HEB mixers; SSPD; SNSPD; NbN films; Nb films
AB We report on transient measurements of electron energy relaxation in NbN films with 300-fs time resolution. Using an electro-optic sampling technique, we have studied the photoresponse of 3.5-nm-thick NbN films deposited on sapphire substrates and exposed to 100-fs-wide optical pulses. Our experimental data analysis was based on the two-temperature model and has shown that in our films at the superconducting transition 10.5 K the inelastic electron-phonon scattering time was about (111}+-__.2) ps. This response time indicated that the maximum intermediate-frequency band of a NbN hot-electron phonon-cooled mixer should reach (16+41-3) GHz if one eliminates the bolometric phonon-heating effect. We have suggested several ways to increase the effectiveness of phonon cooling to achieve the above intrinsic value of the NbN mixer bandwidth.
ER