Мошкова, М. А., Дивочий, А. В., Морозов, П. В., Золотов, Ф. И., Вахтомин, Ю. Б., & Смирнов, К. В. (2018). Высокоэффективные NBN однофотонные детекторы с разрешением числа фотонов. In Сборн. науч. труд. VII международн. конф. по фотонике и информац. опт. (pp. 400–401).
Abstract: Разработаны и исследованы сверхпроводниковые однофотонные детекторы, способные к разрешению до 3-х фотонов в коротком импульсе излучения и имеющие квантовую эффективность детектирования одиночных фотонов ~60% на длине волны lambda=1.55 мкм. Проведенная модернизация технологии изготовления детекторов, позволила получить приемные устройства с мультифотонной квантовой эффективностью, приближающейся к расчетным значениям.
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Симонов, Н. О., Флоря, И. Н., Корнеева, Ю. П., Корнеев, А. А., & Гольцман, Г. Н. (2018). Однофотонный отклик в тонких сверхпроводящих MoNx пленках. In Сборн. науч. труд. VII международн. конф. по фотонике и информац. опт. (pp. 408–409).
Abstract: Продемонстрирован однофотонный отклик, при токе близком к критическому, в MoNx сверхпроводящих полосках шириной 70-104 нм. MoNx детекторы, имеющие коэффициент диффузии D≈0.32 см2/с и время электрон-фононного взаимодействия ηe-ph≈300 пс, достигают квантовой эффективности QE≈20% на длине волны λ=1550 нм. Возможность реализации однофотонного детектора в данном материале, подтверждает существующую теорию вихревого механизма возникновения фотоотклика в узких сверхпроводящих полосках.
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Золотов, Ф. И., Дивочий, А. В., Вахтомин, Ю. Б., Пентин, И. В., Морозов, П. В., Селезнев, В. А., et al. (2018). Применение тонких сверхпроводниковых пленок нитрида ванадия для изготовления счетчиков одиночных ИК-фотонов. In Сборн. науч. труд. VII международн. конф. по фотонике и информац. опт. (pp. 60–61).
Abstract: Получены первые результаты по применению сверхпроводниковых пленок нитрида ванадия (VN) для детекторов одиночных фотонов ИК-диапазона. Изучение сверхпроводниковых однофотонных детекторов (SSPD), изготовленных на основе ультратонких (~5 нм) пленок VN, показало возможность создания устройств с близкой к насыщению зависимостью квантовой эффективности от тока смещения детекторов в телекоммуникационном диапазоне длин волн. Также нами были исследованы кинетическая индуктивность изготовленных структур с различной длиной сверхпроводниковой полоски и времена релаксации электронов в тонких сверхпроводниковых пленках VN.
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Nikoghosyan, A. S., Martirosyan, R. M., Hakhoumian, A. A., Makaryan, A. H., Tadevosyan, V. R., Goltsman, G. N., et al. (2018). Effect of absorption on the efficiency of THz radiation generation in a nonlinear crystal placed into a waveguide. Armenian J. Phys., 11(4), 257–262.
Abstract: The effect of THz radiation absorption on the efficiency of generation of coherent THz radiation in a nonlinear optical crystal placed into a metal rectangular waveguide is studied. The efficiency of the nonlinear conversion of optical laser radiation to the THz band is also a function of the phase-matching (PM) condition inside the nonlinear crystal. The method of partial filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. Phase matching was obtained by the proper choice of the thickness of the nonlinear crystal, namely the degree of partial filling of the waveguide. We have studied the THz radiation attenuation caused by the losses in both the metal walls of the waveguide and in the crystal, taking into account the dimension of the cross section of the waveguide, the degree of partial filling and its dielectric constant.
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Korneeva, Y. P., Vodolazov, D. Y., Semenov, A. V., Florya, I. N., Simonov, N., Baeva, E., et al. (2018). Optical single photon detection in micron-scaled NbN bridges. arXiv:1802.02881v1 [cond-mat.supr-con].
Abstract: We demonstrate experimentally that single photon detection can be achieved in micron-wide NbN bridges, with widths ranging from 0.53 μm to 5.15 μm and for photon-wavelengths from 408 nm to 1550 nm. The microbridges are biased with a dc current close to the experimental critical current, which is estimated to be about 50 % of the theoretically expected depairing current. These results offer an alternative to the standard superconducting single-photon detectors (SSPDs), based on nanometer scale nanowires implemented in a long meandering structure. The results are consistent with improved theoretical modelling based on the theory of non-equilibrium superconductivity including the vortex-assisted mechanism of initial dissipation.
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Tretyakov, I., Kaurova, N., Voronov, B. M., & Goltsman, G. N. (2018). About effect of the temperature operating conditions on the noise temperature and noise bandwidth of the terahertz range NbN hot-electron bolometers. In Proc. 29th Int. Symp. Space Terahertz Technol. (113).
Abstract: Results of an experimental study of the noise temperature (Tn) and noise bandwidth (NBW) of the superconductor NbN hot-electron bolometer (HEB) mixer as a function of its temperature (Tb) and NbN bridge length are presented. It was determined that the NBW of the mixer is significantly wider at temperatures close to the critical ones (Tc) than are values measured at 4.2 K. The NBW of the mixer measured at the heterodyne frequency of 2.5 THz at temperature Tb close to Tc was ~13 GHz, as compared with 6 GHz at Tb = 4.2 K. This experiment clearly demonstrates the limitation of the thermal flow from the NbN bridge at Tb ≪ Tc for mixers manufactured by the in situ technique. This limitation is close in its nature to the Andreev reflection on the superconductor/metal boundary. In this case, the noise temperature of the studied mixer increased from 1100 to 3800 K.
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Sych, D., Shcherbatenko, M., Elezov, M., & Goltsman, G. N. (2018). Towards the improvement of the heterodyne receiver sensitivity beyond the quantum noise limit. In Proc. 29th Int. Symp. Space Terahertz Technol. (pp. 245–247).
Abstract: Noise reduction in heterodyne receivers of the terahertz range is an important issue for astronomical applications. Quantum fluctuations, also known as shot noise, prohibit errorless measurements of the amplitude of electro-magnetic waves, and introduce the so-called standard quantum limit (SQL) on the minimum error of the heterodyne measurements. Nowadays, the sensitivity of modern heterodyne receivers approaches the SQL, and the growing demand for the improvement of measurement precision stimulates a number of both theoretical and experimental efforts to design novel measurement techniques aimed at overcoming the SQL. Here we demonstrate the first steps towards the practical implementation of a sub-SQL quantum receiver. As the principal resources, it requires a highly efficient single-photon counting detector and an interferometer-based scheme for mixing the signal with a low-power local oscillator. We describe the idea of such receiver and its main components.
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Sidorova, M., Semenov, A., Korneev, A., Chulkova, G., Korneeva, Y., Mikhailov, M., et al. (2018). Electron-phonon relaxation time in ultrathin tungsten silicon film. arXiv:1607.07321v1 [physics.ins-det].
Abstract: Using amplitude-modulated absorption of sub-THz radiation (AMAR) method, we studied electron-phonon relaxation in thin disordered films of tungsten silicide. We found a response time ~ 800 ps at critical temperature Tc = 3.4 K, which scales as minus 3 in the temperature range from 1.8 to 3.4 K. We discuss mechanisms, which can result in a strong phonon bottle-neck effect in a few nanometers thick film and yield a substantial difference between the measured time, characterizing response at modulation frequency, and the inelastic electron-phonon relaxation time. We estimate the electron-phonon relaxation time to be in the range ~ 100-200 ps at 3.4 K.
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Sidorova, M. V., Kozorezov, A. G., Semenov, A. V., Korneev, A. A., Chulkova, G. M., Korneeva, Y. P., et al. (2018). Non-bolometric bottleneck in electron-phonon relaxation in ultra-thin WSi film. arXiv:1607.07321v4 [physics.ins-det].
Abstract: We developed the model of the internal phonon bottleneck to describe the energy exchange between the acoustically soft ultrathin metal film and acoustically rigid substrate. Discriminating phonons in the film into two groups, escaping and nonescaping, we show that electrons and nonescaping phonons may form a unified subsystem, which is cooled down only due to interactions with escaping phonons, either due to direct phonon conversion or indirect sequential interaction with an electronic system. Using an amplitude-modulated absorption of the sub-THz radiation technique, we studied electron-phonon relaxation in ultrathin disordered films of tungsten silicide. We found an experimental proof of the internal phonon bottleneck. The experiment and simulation based on the proposed model agree well, resulting in tau{e-ph} = 140-190 ps at TC = 3.4 K, supporting the results of earlier measurements by independent techniques.
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Райтович, А. А., Пентин, И. В., Золотов, Ф. И., Селезнев, В. А., Вахтомин, Ю. Б., & Смирнов, К. В. (2018). Время энергетической релаксации электронов в сверхпроводниковых VN наноструктурах. In Сборник трудов 13 Всероссийской конференции молодых ученых (pp. 236–238). Техно-Декор.
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Fedorov, G., Gayduchenko, I., Titova, N., Gazaliev, A., Moskotin, M., Kaurova, N., et al. (2018). Carbon nanotube based schottky diodes as uncooled terahertz radiation detectors. Phys. Status Solidi B, 255(1), 1700227 (1 to 6).
Abstract: Despite the intensive development of the terahertz technologies in the last decade, there is still a shortage of efficient room‐temperature radiation detectors. Carbon nanotubes (CNTs) are considered as a very promising material possessing many of the features peculiar for graphene (suppression of backscattering, high mobility, etc.) combined with a bandgap in the carrier spectrum. In this paper, we investigate the possibility to incorporate individual CNTs into devices that are similar to Schottky diodes. The latter is currently used to detect radiation with a frequency up to 50 GHz. We report results obtained with semiconducting (bandgap of about 0.5 eV) and quasi‐metallic (bandgap of few meV) single‐walled carbon nanotubes (SWNTs). Semiconducting CNTs show better performance up to 300 GHz with responsivity up to 100 V W−1, while quasi‐metallic CNTs are shown to operate up to 2.5 THz.
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Tretyakov, I. V., Anfertyev, V. A., Revin, L. S., Kaurova, N. S., Voronov, B. M., Vaks, V. L., et al. (2018). Sensitivity and resolution of a heterodyne receiver based on the NbN HEB mixer with a quantum-cascade laser as a local oscillator. Radiophys. Quant. Electron., 60(12), 988–992.
Abstract: We present the results of experimental studies of the basic characteristics and operation features of a terahertz heterodyne detector based on the superconducting NbN HEB mixer and a quantum cascade laser as a local oscillator operating at a frequency of 2.02 THz. The measured noise temperature of such a mixer amounted to 1500 K. The spectral resolution of the detector is determined by the width of the local-oscillator spectral line whose measured value does not exceed 1 MHz. The quantum-cascade laser could be linearly tuned with respect to frequency with the coefficient 7.2 MHz/mA within the limits of the current oscillation bandwidth.
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Gayduchenko, I. A., Moskotin, M. V., Matyushkin, Y. E., Rybin, M. G., Obraztsova, E. D., Ryzhii, V. I., et al. (2018). The detection of sub-terahertz radiation using graphene-layer and graphene-nanoribbon FETs with asymmetric contacts. In Materials Today: Proc. (Vol. 5, pp. 27301–27306).
Abstract: We report on the detection of sub-terahertz radiation using single layer graphene and graphene-nanoribbon FETs with asymmetric contacts (one is the Schottky contact and one – the Ohmic contact). We found that cutting graphene into ribbons a hundred nanometers wide leads to a decrease of the response to sub-THz radiation. We show that suppression of the response in the graphene nanoribbons devices can be explained by unusual properties of the Schottky barrier on graphene-vanadium interface.
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Shurakov, A., Mikhalev, P., Mikhailov, D., Mityashkin, V., Tretyakov, I., Kardakova, A., et al. (2018). Ti/Au/n-GaAs planar Schottky diode with a moderately Si-doped matching sublayer. Microelectronic Engineering, 195, 26–31.
Abstract: In this paper, we report on the results of the study of the Ti/Au/n-GaAs planar Schottky diodes (PSD) intended for the wideband detection of terahertz radiation. The two types of the PSD devices were compared having either the dual n/n+ silicon dopant profile or the triple one with a moderately doped matching sublayer inserted. All the diodes demonstrated no noticeable temperature dependence of ideality factors and barrier heights, whose values covered the ranges of 1.15–1.50 and 0.75–0.85 eV, respectively. We observed the lowering of the flat band barrier height of ∼80 meV after introducing the matching sublayer into the GaAs sandwich. For both the devices types, the series resistance value as low as 20 Ω was obtained. To extract the total parasitic capacitance, we performed the Y-parameters analysis within the electromagnetic modeling of the PSD's behavior via the finite-element method. The capacitance values of 12–12.2 fF were obtained and further verified by measuring the diodes' response voltages in the frequency range of 400–480 GHz. We also calculated the AC current density distribution within the layered structures similar to those being experimentally studied. It was demonstrated that insertion of the moderately Si-doped matching sublayer might be beneficial for implementation of a PSD intended for the operation within the ‘super-THz’ frequency range.
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Bandurin, D. A., Svintsov, D., Gayduchenko, I., Xu, S. G., Principi, A., Moskotin, M., et al. (2018). Resonant terahertz detection using graphene plasmons. Nat. Commun., 9, 5392 (1 to 8).
Abstract: Plasmons, collective oscillations of electron systems, can efficiently couple light and electric current, and thus can be used to create sub-wavelength photodetectors, radiation mixers, and on-chip spectrometers. Despite considerable effort, it has proven challenging to implement plasmonic devices operating at terahertz frequencies. The material capable to meet this challenge is graphene as it supports long-lived electrically tunable plasmons. Here we demonstrate plasmon-assisted resonant detection of terahertz radiation by antenna-coupled graphene transistors that act as both plasmonic Fabry-Perot cavities and rectifying elements. By varying the plasmon velocity using gate voltage, we tune our detectors between multiple resonant modes and exploit this functionality to measure plasmon wavelength and lifetime in bilayer graphene as well as to probe collective modes in its moire minibands. Our devices offer a convenient tool for further plasmonic research that is often exceedingly difficult under non-ambient conditions (e.g. cryogenic temperatures) and promise a viable route for various photonic applications.
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