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| Author | Semenov, A. D.; Nebosis, R. S.; Gousev, Yu. P.; Heusinger, M. A.; Renk, K. F. | ||||
| Title | Analysis of the nonequilibrium photoresponse of superconducting films to pulsed radiation by use of a two-temperature model | Type | Journal Article | ||
| Year | 1995 | Publication | Phys. Rev. B | Abbreviated Journal | Phys. Rev. B |
| Volume | 52 | Issue | 1 | Pages | 581-590 |
| Keywords | HEB, NbN phonon scecific heat, Cp | ||||
| Abstract | Photoresponse of a superconducting film in the resistive state to pulsed radiation has been studied in the framework of a model assuming that two different effective temperatures can be assigned to the quasiparticle and phonon nonequilibrium distributions. The coupled electron-phonon-substrate system is described by a system of time-dependent energy-balance differential equations for effective temperatures. An analytical solution of the system is given and calculated voltage transients are compared with experimental photoresponse signals taking into account the radiation pulse shape and the time resolution of the readout electronics. It is supposed that a resistive state (vortices, fluxons, network of intergrain junctions, hot spots, phase slip centers) provides an ultrafast connection between electron temperature changes and changes of the film resistance and thus plays a minor role in the temporal evolution of the response. In accordance with experimental observations a two-component response was revealed from simulations. The slower component corresponds to a bolometric mechanism while the fast component is connected with the relaxation of the electron temperature. Calculated photoresponse transients are presented for different ratios of the electron and phonon specific heat, radiation pulse durations and fluences, and frequency band passes of registration electronics. From the amplitude of the bolometric component we determine the radiation energy absorbed in a film. This enables us to reveal an intrinsic electron-phonon scattering time even if it is much shorter than the time resolution of readout electronics. We analyze experimental voltage transients for NbN, YBa2Cu3O7, and TlBa2Ca2Cu3O9 superconducting films and find the electron-phonon interaction times at the transition temperatures of 17, 2.5, and 1.8 ps, respectively. The values are in reasonable agreement with data of other experiments. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 903 | |||
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| Author | Khosropanah, Pourya | ||||
| Title | NbN and NbTiN hot electron bolometer THz mixers | Type | Book Whole | ||
| Year | 2003 | Publication | Chalmers University of Technology | Abbreviated Journal | |
| Volume | Issue | Pages | |||
| Keywords | HEB mixer, hot electron bolometer mixer, NbN, NbTiN, superconducting detector, heterodyne receiver, THz mixer, submillimeter mixer, quasioptical receiver, double slot antenna, twin slot antenna, spiral antenna, receiver noise, FTS, Fourier Transform Spectrometer | ||||
| Abstract | The thesis reports the development of Hot Electron Bolometer (HEB) mixers for radio astronomy heterodyne receivers in THz frequency range. Part of this work is the fabrication of HEB devices, which are based on NbN or NbTiN superconducting thin films (â‰<a4>5 nm). They are integrated with wideband spiral or double-slot planar antennas. The mixer chips are incorporated into a quasi-optical receiver. The experimental part of this work focuses on the characterization of the receiver as a whole, and the HEB mixers as a part. Double side band receiver noise temperature and the IF bandwidth are reported for frequencies from 0.7 THz up to 2.6 THz. The spectrum of the direct response of HEB integrated with dierent antennas are measured using Fourier Transform Spectrometer (FTS). The effect of the bolometer size on total receiver performance and the LO power requirements is also discussed. A high-yield and reliable process for fabrication of NbN HEB mixers have been achieved. Over 100 devices with different bolometer geometry, film property and also different antennas have been fabricated and measured. The measured data enables us to discuss the impact of different parameters to the receiver overall performance. This work has provided NbN HEB mixers to the following receivers: TREND (Terahertz REceiver with NbN HEB Device) operating at 1.25-1.5 THz, installed in AST/RO Submillimeter Wave Telescope, Amundsen/Scott South Pole Station, in 2002-2003. Band 6-low (1.410-1.700 THz) and 6-high (1.700-1.920 THz) of the HIFI (Heterodyne Instrument for Far Infra-red) in the Herschel Space Observatory, due to launch in 2007 by ESA (European Space Agency). Besides, there has been continuous efforts to develop better models to explain the mixer performance more accurately. They are based on two temperature model for electrons and phonons and solving one-dimensional heat balance equations along the bolometer. The principles of these models are illustrated and the calculated results are compared with measured data. |
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| Corporate Author | Thesis | Ph.D. thesis | |||
| Publisher | Chalmers University of Technology | Place of Publication | Göteborg | Editor | |
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| Notes | Approved | no | |||
| Call Number | Serial | 910 | |||
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| Author | Yagoubov, P.; Kroug, M.; Merkel, H.; Kollberg, E.; Gol'tsman, G.; Svechnikov, S.; Gershenzon, E. | ||||
| Title | Noise temperature and local oscillator power requirement of NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies | Type | Journal Article | ||
| Year | 1998 | Publication | Appl. Phys. Lett. | Abbreviated Journal | Appl. Phys. Lett. |
| Volume | 73 | Issue | 19 | Pages | 2814-2816 |
| Keywords | NbN HEB mixers, noise temperature, local oscillator power | ||||
| Abstract | In this letter, the noise performance of NbN-based phonon-cooled hot electron bolometric quasioptical mixers is investigated in the 0.55–1.1 THz frequency range. The best results of the double-sideband <cd><2018>DSB<cd><2019> noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz, and 1250 K at 1.1 THz. The water vapor in the signal path causes significant contribution to the measured receiver noise temperature around 1.1 THz. The devices are made from 3-nm-thick NbN film on high-resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are typically 0.2Ï«2 um. The amount of local oscillator power absorbed in the bolometer is less than 100 nW. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 911 | |||
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| Author | Miao, W.; Zhang, W.; Zhong, J. Q.; Shi, S. C.; Delorme, Y.; Lefevre, R.; Feret, A; Vacelet, T | ||||
| Title | Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges | Type | Journal Article | ||
| Year | 2014 | Publication | Appl. Phys. Lett. | Abbreviated Journal | <ef><bf><bc>Appl. Phys. Lett. |
| Volume | 104 | Issue | Pages | 052605(1-4) | |
| Keywords | NbN HEB mixers, local oscillator power, RF nonuniform absorption | ||||
| Abstract | We interpret the experimental observation of a frequency-dependence of superconducting hot electron bolometer (HEB) mixers by taking into account the non-uniform absorption of the terahertz radiation on the superconducting HEB microbridge. The radiation absorption is assumed to be proportional to the local surface resistance of the HEB microbridge, which is computed using the Mattis-Bardeen theory. With this assumption the dc and mixing characteristics of a superconducting niobium-nitride (NbN) HEB device have been modeled at frequencies below and above the equilibrium gap frequency of the NbN film. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 935 | |||
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| Author | Kovalyuk, V.; Hartmann, W.; Kahl, O.; Kaurova, N.; Korneev, A.; Goltsman, G.; Pernice, W. H. P. | ||||
| Title | Absorption engineering of NbN nanowires deposited on silicon nitride nanophotonic circuits | Type | Journal Article | ||
| Year | 2013 | Publication | Opt. Express | Abbreviated Journal | Opt. Express |
| Volume | 21 | Issue | 19 | Pages | 22683-22692 |
| Keywords | SSPD, SNSPD, NbN nanoeires, Si3N4 waveguides | ||||
| Abstract | We investigate the absorption properties of U-shaped niobium nitride (NbN) nanowires atop nanophotonic circuits. Nanowires as narrow as 20nm are realized in direct contact with Si3N4 waveguides and their absorption properties are extracted through balanced measurements. We perform a full characterization of the absorption coefficient in dependence of length, width and separation of the fabricated nanowires, as well as for waveguides with different cross-section and etch depth. Our results show excellent agreement with finite-element analysis simulations for all considered parameters. The experimental data thus allows for optimizing absorption properties of emerging single-photon detectors co-integrated with telecom wavelength optical circuits. | ||||
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| ISSN | 1094-4087 | ISBN | Medium | ||
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| Notes | PMID:24104155 | Approved | no | ||
| Call Number | Serial | 1213 | |||
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