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Zolotov, P. I., Divochiy, A. V., Vakhtomin, Y. B., Morozov, P. V., Seleznev, V. A., & Smirnov, K. V. (2017). Development of high-effective superconducting single-photon detectors aimed for mid-IR spectrum range. In J. Phys.: Conf. Ser. (Vol. 917, 062037).
Abstract: We report on development of superconducting single-photon detectors (SSPD) with high intrinsic quantum efficiency in the wavelength range 1.31 – 3.3 μm. By optimization of the NbN film thickness and its compound, we managed to improve detection efficiency of the detectors in the range up to 3.3 μm. Optimized devices showed intrinsic quantum efficiencies as high as 10% at mid-IR range.
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Romanov, N. R., Zolotov, P. I., Vakhtomin, Y. B., Divochiy, A. V., & Smirnov, K. V. (2018). Electron diffusivity measurements of VN superconducting single-photon detectors. In J. Phys.: Conf. Ser. (Vol. 1124, 051032).
Abstract: The research of ultrathin vanadium nitride (VN) films as a promising candidate for superconducting single-photon detectors (SSPD) is presented. The electron diffusivity measurements are performed for such devices. Devices that were fabricated out from 9.9 nm films had diffusivity coefficient of 0.41 cm2/s and from 5.4 nm – 0.54 cm2/s. Obtained values are similar to other typical SSPD materials. The diffusivity that increases along with decreasing of the film thickness is expected to allow fabrication of the devices with improved characteristics. Fabricated VN SSPDs showed prominent single-photon response in the range 0.9-1.55 µm.
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Zolotov, P., Vakhtomin, Y., Divochiy, A., Seleznev, V., Morozov, P., & Smirnov, K. (2013). High-efficiency single-photon detectors based on NbN films.
Abstract: We present our resent results in development and testing of Superconducting Single-Photon Detectors (SSPD) with detection efficiencies greater than 85%. High values of obtained results are assigned to proposed design of the detector with integrated resonator structure, including two-layer optical cavity and anti-reflective coating (ARC).
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Moshkova, M., Divochiy, A., Morozov, P., Vakhtomin, Y., Antipov, A., Zolotov, P., et al. (2019). High-performance superconducting photon-number-resolving detectors with 86% system efficiency at telecom range. J. Opt. Soc. Am. B, 36(3), B20.
Abstract: The use of improved fabrication technology, highly disordered NbN thin films, and intertwined section topology makes it possible to create high-performance photon-number-resolving superconducting single-photon detectors (PNR SSPDs) that are comparable to conventional single-element SSPDs at the telecom range. The developed four-section PNR SSPD has simultaneously an 86±3% system detection efficiency, 35 cps dark count rate, ∼2 ns dead time, and maximum 90 ps jitter. An investigation of the PNR SSPD’s detection efficiency for multiphoton events shows good uniformity across sections. As a result, such a PNR SSPD is a good candidate for retrieving the photon statistics for light sources and quantum key distribution systems.
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Vasilev, D. D., Malevannaya, E. I., Moiseev, K. M., Zolotov, P. I., Antipov, A. V., Vakhtomin, Y. B., et al. (2020). Influence of deposited material energy on superconducting properties of the WSi films. In IOP Conf. Ser.: Mater. Sci. Eng. (Vol. 781, 012013 (1 to 6)).
Abstract: WSi thin films have the advantages for creating SNSPDs with a large active area or array of detectors on a single substrate due to the amorphous structure. The superconducting properties of ultrathin WSi films substantially depends on their structure and thickness as the NbN films. Scientific groups investigating WSi films mainly focused only on changes of their thickness and the ratio of the components on the substrate at room temperature. This paper presents experiments to determine the effect of the bias potential on the substrate, the temperature of the substrate, and the peak power of pulsed magnetron sputtering, which is the equivalent of ionization, a tungsten target, on the surface resistance and superconducting properties of the WSi ultrathin films. The negative effect of the substrate temperature and the positive effect of the bias potential and the ionization coefficient (peak current) allow one to choose the best WSi films formation mode for SNSPD: substrate temperature 297 K, bias potential -60 V, and peak current 3.5 A.
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