PT Journal
AU Henrich, D
   Dorner, S
   Hofherr, M
   Il'in, K
   Semenov, A
   Heintze, E
   Scheffler, M
   Dressel, M
   Siegel, M
TI Broadening of hot-spot response spectrum of superconducting NbN nanowire single-photon detector with reduced nitrogen content
JI J. Appl. Phys.
PY 2012
VL 112
LA English
DE SSPD; SNSPD; magnetron sputtering; spectrum; NbN film; nitrogen concentration
AB The spectral detection efficiency and the dark count rate of superconducting nanowiresingle-photon detectors (SNSPD) have been studied systematically on detectors made from thinNbN films with different chemical compositions. Reduction of the nitrogen content in the 4 nmthick NbN films results in a decrease of the dark count rates more than two orders of magnitudeand in a red shift of the cut-off wavelength of the hot-spot SNSPD response. The observedphenomena are explained by an improvement of uniformity of NbN films that has been confirmedby a decrease of resistivity and an increase of the ratio of the measured critical current to thedepairing current. The latter factor is considered as the most crucial for both the cut-offwavelength and the dark count rates of SNSPD. Based on our results we propose a set of criteriafor material properties to optimize SNSPD in the infrared spectral region. VC 2012 AmericanInstitute of Physics. [http://dx.doi.org/10.1063/1.4757625]
ER