Large Signal Amplitude and Bias Range of Cascade Switch Superconducting Nanowire Single Photon Detectors

M. Ejrnaes, A. Casaburi, O. Quaranta, S. Marchetti, A. Gaggero,
F. Mattioli, R. Leoni, S. Pagano, and R. Cristiano

Abstract— Cascade switch superconducting nanowire single photon detectors has been fabricated of ultrathin NbN films deposited by DC-magnetron sputtering at room temperature on MgO substrates. Detectors using 4 to 24 nanowires in parallel, having an area coverage of 5x6 µm² and a filling factor of 40%, have been investigated. Signal amplitudes increase with the number of parallel nanowires and reaches 12.3 mV with a signal noise of 20 µV. The range of bias currents where the detectors emit signal pulses also increase with the number of parallel nanowires and exceeds the nanowire critical current.

Index Terms — Nanotechnology, Superconducting radiation detectors, Infrared detectors, Thin films.

Manuscript received 19 August 2008.
This work was performed in the framework of the EU project “SINPHONIA” NMP4-CT-2005-016433.
.M. Ejrnaes. M. Ejrnaes and R. Cristiano are with the C.N.R.-Institute of Cybernetics, Pozzuoli, 80078 (NA), Italy (phone: +39-081-867-5270; fax: +39-081-867-5128; e-mail: m.ejrnaes@cib.na.cnr.it).
A. Casaburi and S. Pagano are with the Department of Physics “E. R. Caianiello”, University of Salerno, 84081 Baronissi, Italy and the C.N.R.-Institute of Cybernetics, Pozzuoli, 80078 (NA), Italy.
O. Quaranta and S. Marchetti are with the Department of Physics “E. R. Caianiello”, University of Salerno, 84081 Baronissi, Italy.
A. Gaggero, F. Mattioli, and R. Leoni are with C.N.R.-Institute of Photonics and Nanotechnologies, 00156 Roma, Italy.

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