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ST172 - Superconducting Nanowire Single-photon Detectors: Quantum Efficiency vs. Thickness of NbN Films

Superconducting Nanowire Single-photon Detectors: Quantum Efficiency vs. Thickness of NbN Films

M. Hofherr1, D. Rall1, K. S. Ilin1, A. Semenov2,
N. Gippius3 and H.-W. Hübers2 and M. Siegel1

1Institut für Mikro- und Nanoelektronische Systeme,
Universität Karlsruhe, Karlsruhe, Germany
2DLR Institut für Planetenforschung, Berlin, Germany
3LASMEA, CNRS, Universite Blaise Pascal, Aubiere, France

E-mail: [email protected]

ABSTRACT - The quantum efficiency (QE) of thin NbN superconducting nanowire single-photon detectors (SNSPD) has been systematically studied in a wide spectral range from 400 to 2000 nm radiation wavelength. SNSPDs were made from thin NbN films with thickness between 4 and 12 nm deposited on sapphire substrates. The observed reduction of QE with increasing radiation wavelength is caused by a crossover from the “hot-spot” to the “vortex” mechanism of the nanowire detector response. The crossover wavelength shifts to shorter wavelengths with increasing thickness of NbN films.

IEEE/CSC & ESAS EUROPEAN SUPERCONDUCTIVITY NEWS FORUM (ESNF), No. 11, January 2010
Published in Journal of Physics Conf. Series (SuST234, 012017 (2010)