| Records |
| Author |
Pentin, I.; Vakhtomin, Y.; Seleznev, V.; Smirnov, K. |
| Title |
Hot electron energy relaxation time in vanadium nitride superconducting film structures under THz and IR radiation |
Type |
Journal Article |
Year  |
2020 |
Publication |
Sci. Rep. |
Abbreviated Journal |
Sci. Rep. |
| Volume |
10 |
Issue |
1 |
Pages |
16819 |
| Keywords |
VN HEB |
| Abstract |
The paper presents the experimental results of studying the dynamics of electron energy relaxation in structures made of thin (d approximately 6 nm) disordered superconducting vanadium nitride (VN) films converted to a resistive state by high-frequency radiation and transport current. Under conditions of quasi-equilibrium superconductivity and temperature range close to critical (~ Tc), a direct measurement of the energy relaxation time of electrons by the beats method arising from two monochromatic sources with close frequencies radiation in sub-THz region (omega approximately 0.140 THz) and sources in the IR region (omega approximately 193 THz) was conducted. The measured time of energy relaxation of electrons in the studied VN structures upon heating of THz and IR radiation completely coincided and amounted to (2.6-2.7) ns. The studied response of VN structures to IR (omega approximately 193 THz) picosecond laser pulses also allowed us to estimate the energy relaxation time in VN structures, which was ~ 2.8 ns and is in good agreement with the result obtained by the mixing method. Also, we present the experimentally measured volt-watt responsivity (S~) within the frequency range omega approximately (0.3-6) THz VN HEB detector. The estimated values of noise equivalent power (NEP) for VN HEB and its minimum energy level (deltaE) reached NEP@1MHz approximately 6.3 x 10(-14) W/ radicalHz and deltaE approximately 8.1 x 10(-18) J, respectively. |
| Address |
National Research University Higher School of Economics, 20 Myasnitskaya Str., Moscow, 101000, Russia |
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2045-2322 |
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PMID:33033360; PMCID:PMC7546726 |
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no |
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1797 |
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| Author |
Vasilev, D. D.; Malevannaya, E. I.; Moiseev, K. M.; Zolotov, P. I.; Antipov, A. V.; Vakhtomin, Y. B.; Smirnov, K. V. |
| Title |
Influence of deposited material energy on superconducting properties of the WSi films |
Type |
Conference Article |
| Year |
2020 |
Publication |
IOP Conf. Ser.: Mater. Sci. Eng. |
Abbreviated Journal |
IOP Conf. Ser.: Mater. Sci. Eng. |
| Volume |
781 |
Issue |
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Pages |
012013 (1 to 6) |
| Keywords |
WSi SSPD, SNSPD |
| 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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1757-899X |
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1798 |
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Antipov, A. V.; Seleznev, V. A.; Vakhtomin, Y. B.; Morozov, P. V.; Vasilev, D. D.; Malevannaya, E. I.; Moiseev, K. M.; Smirnov, K. |
| Title |
Investigation of WSi and NbN superconducting single-photon detectors in mid-IR range |
Type |
Conference Article |
| Year |
2020 |
Publication |
IOP Conf. Ser.: Mater. Sci. Eng. |
Abbreviated Journal |
IOP Conf. Ser.: Mater. Sci. Eng. |
| Volume |
781 |
Issue |
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Pages |
012011 (1 to 5) |
| Keywords |
WSi, NbN SSPD, SNSPD |
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Spectral characteristics of WSi and NbN superconducting single-photon detectors with different surface resistance and width of nanowire strips have been investigated in the wavelength range of 1.3-2.5 μm. WSi structures with narrower strips demonstrated better performance for detection of single photons in longer wavelength range. The difference in normalized photon count rate for such structures reaches one order of magnitude higher in comparison with structures based on NbN thin films at 2.5 μm. |
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1757-899X |
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1799 |
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Zhang, X.; Lita, A. E.; Smirnov, K.; Liu, H. L.; Zhu, D.; Verma, V. B.; Nam, S. W.; Schilling, A. |
| Title |
Strong suppression of the resistivity near the superconducting transition in narrow microbridges in external magnetic fields |
Type |
Journal Article |
| Year |
2020 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
101 |
Issue |
6 |
Pages |
060508 (1 to 6) |
| Keywords |
MoSi, WSi films |
| Abstract |
We have investigated a series of superconducting bridges based on homogeneous amorphous WSi and MoSi films, with bridge widths w ranging from 2 to 1000μm and film thicknesses d∼4−6 and 100 nm. Upon decreasing the bridge widths below the respective Pearl lengths, we observe in all cases distinct changes in the characteristics of the resistive transitions to superconductivity. For each of the films, the resistivity curves R(B,T) separate at a well-defined and field-dependent temperature T∗(B) with decreasing the temperature, resulting in a dramatic suppression of the resistivity and a sharpening of the transitions with decreasing bridge width w. The associated excess conductivity in all the bridges scales as 1/w, which may suggest either the presence of a highly conducting region that is dominating the electric transport, or a change in the vortex dynamics in narrow enough bridges. We argue that this effect can only be observed in materials with sufficiently weak vortex pinning. |
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2469-9950 |
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1800 |
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Tretyakov, I.; Shurakov, A.; Perepelitsa, A.; Kaurova, N.; Svyatodukh, S.; Zilberley, T.; Ryabchun, S.; Smirnov, M.; Ovchinnikov, O.; Goltsman, G. |
| Title |
Room temperature silicon detector for IR range coated with Ag2S quantum dots |
Type |
Journal Article |
| Year |
2019 |
Publication |
Phys. Status Solidi RRL |
Abbreviated Journal |
Phys. Status Solidi RRL |
| Volume |
13 |
Issue |
9 |
Pages |
1900187-(1-6) |
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For decades, silicon has been the chief technological semiconducting material of modern microelectronics and has a strong influence on all aspects of the society. Applications of Si-based optoelectronic devices are limited to the visible and near infrared (IR) ranges. For photons with an energy less than 1.12 eV, silicon is almost transparent. The expansion of the Si absorption to shorter wavelengths of the IR range is of considerable interest for optoelectronic applications. By creating impurity states in Si, it is possible to cause sub-bandgap photon absorption. Herein, an elegant and effective technology of extending the photo-response of Si toward the IR range is presented. This approach is based on the use of Ag 2 S quantum dots (QDs) planted on the surface of Si to create impurity states in the Si bandgap. The specific sensitivity of the room temperature zero-bias Si_Ag 2 Sp detector is 10 11 cm Hz W 1 at 1.55 μm. Given the variety of available QDs and the ease of extending the photo-response of Si toward the IR range, these findings open a path toward future studies and development of Si detectors for technological applications. The current research at the interface of physics and chemistry is also of fundamental importance to the development of Si optoelectronics. |
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1862-6254 |
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1149 |
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