Superconducting detector of IR single-photons based on thin WSi films

V. A. Seleznev; A. Divochiy; Yu. B. Vakhtomin; P. V. Morozov; P. I. Zolotov; D. D. Vasilev; K. M. Moiseev; E. I. Malevannaya; K. V. Smirnov

doi:10.1088/1742-6596/737/1/012032

arXiv · 1606.09406

Superconducting detector of IR single-photons based on thin WSi films

V. A. Seleznev·A. Divochiy·Yu. B. Vakhtomin·P. V. Morozov·P. I. Zolotov·D. D. Vasilev·K. M. Moiseev·E. I. Malevannaya·K. V. Smirnov

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Abstract

We have developed the deposition technology of WSi thin films 4 to 9 nm thick with high temperature values of superconducting transition (Tc~4 K). Based on deposed films there were produced nanostructures with indicative planar sizes ~100 nm, and the research revealed that even on nanoscale the films possess of high critical temperature values of the superconducting transition (Tc~3.3-3.7K ) which certifies high quality and homogeneity of the films created. The first experiments on creating superconducting single-photon detectors showed that the detectors SDE (system detection efficiency) with increasing bias current (Ib) reaches a constant value of ~30% (for 1550 nm) defined by infrared radiation absorption by the superconducting structure. To enhance radiation absorption by the superconductor there were created detectors with cavity structures which demonstrated a practically constant value of quantum efficiency >65% for bias currents Ib>=0.6Ic. The minimal dark counts level (DC) made 1 s^-1 limited with background noise. Hence WSi is the most promising material for creating single-photon detectors with record SDE/DC ratio and noise equivalent power (NEP).

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V. A. Seleznev, A. Divochiy, Yu. B. Vakhtomin, P. V. Morozov, P. I. Zolotov, D. D. Vasilev, K. M. Moiseev, E. I. Malevannaya, K. V. Smirnov. 2016-06-30. Superconducting detector of IR single-photons based on thin WSi films. https://doi.org/10.1088/1742-6596/737/1/012032

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