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Shurakov, A., Mikhailov, D., Belikov, I., Kaurova, N., Zilberley, T., Prikhodko, A., et al. (2020). Planar Schottky diode with a Γ-shaped anode suspended bridge. In J. Phys.: Conf. Ser. (Vol. 1695, 012154).
Abstract: In this paper we report on the fabrication of a planar Schottky diode utilizing a Г-shaped anode suspended bridge. The bridge maintains transition between the top and bottom level planes of a 1.4 µm thick GaAs mesa. To implement the profile of a suspended bridge and inward tilt of a mesa wall adjacent to it, we make use of an anisotropic etching of gallium arsenide. The geometry proposed enables the fabrication of a diode with mesa of an arbitrary thickness to mitigate AC losses in the diode layered structure at terahertz frequencies of interest. For frequencies beyond 1 THz, it is also beneficial to use the geometry for the implementation of n-GaAs/n-InGaAs heterojunction Schottky diodes grown on InP substrate.
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Moskotin, M. V., Gayduchenko, I. A., Goltsman, G. N., Titova, N., Voronov, B. M., Fedorov, G. F., et al. (2018). Bolometric effect for detection of sub-THz radiation with devices based on carbon nanotubes. In J. Phys.: Conf. Ser. (Vol. 1124, 051050 (1 to 5)).
Abstract: In this work we investigate the response on THz radiation of a FET device based on an individual carbon nanotube conductance channel. It was already shown, that the response of such devices can be either of diode rectification origin or of thermoelectric effect origin or of their combination. In this work we demonstrate that at 77K and 8K temperatures strong bolometric effect also makes a significant contribution to the response.
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Smirnov, E., Golikov, A., Zolotov, P., Kovalyuk, V., Lobino, M., Voronov, B., et al. (2018). Superconducting nanowire single-photon detector on lithium niobate. In J. Phys.: Conf. Ser. (Vol. 1124, 051025).
Abstract: We demonstrate superconducting niobium nitride nanowires folded on top of lithium niobate substrate. We report of 6% system detection efficiency at 20 s−1 dark count rate at telecommunication wavelength (1550 nm). Our results shown great potential for the use of NbN nanowires in the field of linear and nonlinear integrated quantum photonics.
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Yang, Z. Q., Hajenius, M., Baselmans, J. J. A., Gao, J. R., Voronov, B., & Gol’tsman, G. N. (2006). Reduced noise in NbN hot-electron bolometer mixers by annealing. Supercond. Sci. Technol., 19(4), L (9 to 12).
Abstract: We find that the sensitivity of heterodyne receivers based on superconducting hot-electron bolometers (HEBs) increases by 25–30% after annealing at 85 °C in vacuum. The devices studied are twin-slot antenna coupled mixers with a small NbN bridge of 1 × 0.15 µm2. We show that annealing changes the device properties as reflected in sharper resistive transitions of the complete device, apparently reducing the device-related noise. The lowest receiver noise temperature of 700 K is measured at a local oscillator frequency of 1.63 THz and a bath temperature of 4.3 K.
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Zhang, W., Li, N., Jiang, L., Miao, W., Lin, Z. - H., Yao, Q. - J., et al. (2007). Noise behaviour of a THz superconducting hot-electron bolometer mixer. Chinese Phys. Lett., 24(6), 1778–1781.
Abstract: A quasi-optical superconducting NbN hot-electron bolometer (HEB) mixer is measured in the frequency range of 0.5–2.5 THz for understanding of the frequency dependence of noise temperature of THz coherent detectors. It has been found that noise temperature increasing with frequency is mainly due to the coupling loss between the quasi-optical planar antenna and the superconducting HEB bridge when taking account of non-uniform distribution of high-frequency current. With the coupling loss corrected, the superconducting HEB mixer demonstrates a noise temperature nearly independent of frequency.
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Voronov, B. M., Gershenzon, E. M., Gol'tsman, G. N., Gubkina, T. O., & Semash, V. D. (1994). Superconductive properties of ultrathin NbN films on different substrates. Sverkhprovodimost': Fizika, Khimiya, Tekhnika, 7(6), 1097–1102.
Abstract: A study was made on dependence of surface resistance, critical temperature and width of superconducting transition on application temperature and thickness of NbN films, which varied within the range of 3-10 nm. Plates of sapphire, fused and monocrystalline quartz, MgO, as well as Si and silicon oxide were used as substrates. NbN films with 160 μθ·cm specific resistance and 16.5 K (Tc) critical temperature were obtained on sapphire substrates. Intensive growth of ΔTc was noted for films, applied on fused quartz, with increase of precipitation temperature. This is explained by occurrence of high tensile stresses in NbN films, caused by sufficient difference of thermal coefficients of expansion of NbN and quartz.
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Budyanskij, M. Y., Sejdman, L. A., Voronov, B. M., & Gubkina, T. O. (1992). Increase of reproducibility in production of superconducting thin films of niobium nitride. Sverkhprovodimost': Fizika, Khimiya, Tekhnika, 5(10), 1950–1954.
Abstract: Technique to control the composition of gas medium in the reactive magnetron discharge and the composition of the deposited films of niobium nitride using electrical parameters of discharge only, in particular, by δU = Up – Uar value at contant stabilized discharge current is described. Technique to select optimal condition for deposition of niobium nitride films when the films have composition meeting chemical formula, is suggested. Thin films of niobium nitride with up to 7 nm thickness and with rather high temperature of transition into superconducting state Tk > 10 K) and with low width of transition (δ < 0.6 K), are obtained. It is determined, that substrate material and dielectric sublayer do not affect. Tk value, while difference in coefficients of thermal expansion of substrate and of film affects δTk value.
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Voronov, B. M., Gershenzon, E. M., Gol'tsman, G. N., Gogidze, I. G., Gusev, Y. P., Zorin, M. A., et al. (1992). Picosecond range detector base on superconducting niobium nitride film sensitive to radiation in spectral range from millimeter waves up to visible light. Sverkhprovodimost': Fizika, Khimiya, Tekhnika, 5(5), 955–960.
Abstract: Fast-operating picosecond detector of electromagnetical radiation is developed on the basis of fine superconducting film of niobium nitride with high sensitivity within spectral range from millimetric waves up to visible light. Detector sensitive element represents structure covering narrow parallel strips with micron sizes included in the rupture of microstrip line. Detecting ability of the detector and time constant measured using amplitude-simulated radiation of reverse wave tubes and pulse radiation of picosecond gas and solid-body lasers, constitute D*≅1010 W-1·cm·Hz-1/2 and τ≤5 ps respectively, at 10 K temperature. The expected value of time constant of the detector at 10 K obtained via extrapolation of directly measured dependence that is, τ ∝ τ-1, constitutes 20 ps. Experimental data demonstrate that detection mechanism is linked with electron heating effect.
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Schwaab, G. W., Sirmain, G., Schubert, J., Hubers, H. - W., Gol'tsman, G., Cherednichenko, S., et al. (1999). Investigation of NbN phonon-cooled HEB mixers at 2.5 THz. IEEE Trans. Appl. Supercond., 9(2), 4233–4236.
Abstract: The development of superconducting hot electron bolometric (HEB) mixers has been a big step forward in the direction of quantum noise limited mixer performance at THz frequencies. Such mixers are crucial for the upcoming generation of airborne and spaceborne THz heterodyne receivers. In this paper we report on new results on a phonon-cooled NbN HEB mixer using e-beam lithography. The superconducting film is 3 nm thick. The mixer is 0.2 μm long and 1.5 μm wide and it is integrated in a spiral antenna on a Si substrate. The device is quasi-optically coupled through a Si lens and a dielectric beam combiner to the radiation of an optically pumped FIR ring gas laser cavity. The performance of the mixer at different THz frequencies from 0.69 to 2.55 THz with an emphasis on 2.52 THz is demonstrated. At 2.52 THz minimum DSB noise temperatures of 4200 K have been achieved at an IF of 1.5 GHz and a bandwidth of 40 MHz with the mixer mounted in a cryostat and a 0.8 m long signal path in air.
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Jiang, L., Antipov, S. V., Voronov, B. M., Gol'tsman, G. N., Zhang, W., Li, N., et al. (2007). Characterization of the performance of a quasi-optical NbN superconducting HEB mixer. IEEE Trans. Appl. Supercond., 17(2), 395–398.
Abstract: In this paper we focus mainly on the investigation of the performance of a quasi-optical (planar log-spiral antenna) phonon-cooled NbN superconducting hot electron bolometer (HEB) mixer, which is cryogenically cooled by a close-cycled 4-K cryocooler, at 500 and 850 GHz frequency bands. The mixer's noise performance, stability of IF output power, and local oscillator (LO) power requirement are characterized for three NbN superconducting HEB devices of different sizes. The transmission characteristics of Mylar and Zitex films with incidence waves of an elliptical polarization are also examined by measuring the mixer's noise temperature. The lowest receiver noise temperatures (with no corrections) of 750 and 1100 K are measured at 500 and 850 GHz, respectively. Experimental results also demonstrate that the bigger the HEB device is, the higher the stability of IF output power becomes.
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