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Author Hübers, Heinz-Wilhelm; Semenov, Alexei; Schubert, Josef; Gol'tsman, Gregory; Voronov, Boris; Gershenzon, Evgeni url  openurl
  Title Performance of the phonon-cooled hot-electron bolometric mixer between 0.7 THz and 5.2 THz Type Conference Article
  Year 2000 Publication Proc. 8-th Int. Conf. on Terahertz Electronics Abbreviated Journal Proc. 8-th Int. Conf. on Terahertz Electronics  
  Volume Issue Pages 117-119  
  Keywords NbN HEB mixers  
  Abstract We report on the phonon cooled NbN hot electron bolometer as mixer in the terahertz frequency range. Its hybrid antenna consists of a hyperhemispheric silicon lens and a logarithmic-spiral feed antenna. Noise temperatures have been measured between 0.7 THz and 5.2 THz. A quarter wavelength layer of Parylene works as antireflection coating for the silicon lens and reduces the noise temperature by about 30. It was found that the antenna pattern at 2.5 THz is determined by the feed antenna and not by the diameter of the lens.  
  Address Darmstadt, Germany  
  Corporate Author Thesis  
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  Area Expedition Conference International Conference on Terahertz Electronics [8th], Held inDarmstadt, Germany on 28-29 September 2000  
  Notes Approved no  
  Call Number Serial 1553  
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Author Darula, Marian; Semenov, Alex D.; Hübers, Heinz-Wilhelm; Schubert, Josef url  openurl
  Title Quasioptical high-Tc superconductor Josephson mixer at terahertz frequencies Type Abstract
  Year 2000 Publication Proc. 11th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 11th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 515  
  Keywords HTS Josephson mixers  
  Abstract Mixers based on Josephson junctions from conventional superconductor materials have demonstrated excellent performance at subgap frequencies. The advantages of Josephson mixers are low optimal power of the local oscillator and large intermediate frequency bandwidth but their noise temperature increases dramatically at frequencies corresponding to the energy gap of the superconductor, which is typically below 1 THz for widely used materials. The large energy gap of oxide superconductors makes them promising candidates for development of terahertz Josephson mixers. Here we report on experimental study of the quasioptical mixer utilizing bicrystal Josephson junction from high-transition-temperature YBa 2 Cu 3 O 7-δ film. Junctions with a width of 2 µm were fabricated from 100 nm thick laser ablated films on bicrystal MgO substrates and had the and the J C R n product of about 2 mV at 4.2 K. The planar complementary logarithmic spiral antenna incorporated into co-planar waveguide was patterned from 200 nm thick gold film thermally evaporated in situ on top of the YBa 2 Cu 3 O 7-δ film. The mixer chip was clamped to the extended hemispherical silicon lens. Performance of the mixer was investigated at 4.5 K bath temperature. We used FIR laser as a local oscillator at frequencies 0.698 and 2.52 THz. System noise temperature (DSB) was determined from Y-factor measured with 300 K and 77 K loads. At 0.698 THz the lowest noise temperature 1750 K was observed when the mixer was biased with the fixed current to the region in the vicinity of either the first Shapiro step or the critical current. Between these two bias points the noise temperature increased to ≈ 20000 K. As function of the local oscillator power the noise temperature reached the minimum when the critical current was suppressed to the half of its equilibrium value. Power of the local oscillator absorbed by the mixer at optimal operation was of the order 100 nW. The present design of our antenna limits the upper operation frequency to the value of 1.8 THz. Nevertheless, we clearly observed Shapiro steps at the frequency 2.52 THz. Bearing in mind an improved design of the antenna, we estimate the 3000 K DSB noise temperature at this frequency.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1555  
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Author Cherednichenko, S.; Rönnung, F.; Gol’tsman, G.; Kollberg, E.; Winkler, D. url  openurl
  Title YBa2Cu3O7-δ hot-electron bolometer mixer at 0.6 THz Type Conference Article
  Year 2000 Publication Proc. 11th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 11th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 517-522  
  Keywords YBCO HTS HEB mixers  
  Abstract We present an investigation of hot-electron bolometric mixer based on a YBa 2 Cu 3 O 7-δ (YBCO) superconducting thin film. Mixer conversion loss of –46 dB, absorbed local oscillator power and intermediate frequency bandwidth were measured at the local oscillator frequency 0.6 THz. The fabrication technique for nanoscale YBCO hot-electron bolometer (HEB) mixer integrated with a planar antenna structure is described.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1556  
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Author Cherednichenko, S.; Kroug, M.; Yagoubov, P.; Merkel, H.; Kollberg, E.; Yngvesson, K. S.; Voronov, B.; Gol’tsman, G. url  openurl
  Title IF bandwidth of phonon cooled HEB mixers made from NbN films on MgO substrates Type Conference Article
  Year 2000 Publication Proc. 11th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 11th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 219-227  
  Keywords NbN HEB mixers, cinversion gain bandwidth, IF bandwidth  
  Abstract An investigation of gain and noise bandwidth of phonon-cooled hot-electron bolometric (HEB) mixers is presented. The radiation coupling to the mixers is quasioptical through either a spiral or twin-slot antenna. A maximum gain bandwidth of 4.8 GHz is obtained for mixers based on a 3.5 nm thin NbN film with Tc= 10 K. The noise bandwidth is 5.6 GHz, at the moment limited by parasitic elements in the, device mount fixture. At 0.65 THz the DSB receiver noise temperature is 700-800 К in the IF band 1-2 GHz, and 1150-2700 К in the band 3.5-7 GHz.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1557  
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Author Semenov, A. D.; Gol’tsman, G. N. url  doi
openurl 
  Title Nonthermal mixing mechanism in a diffusion-cooled hot-electron detector Type Journal Article
  Year 2000 Publication J. Appl. Phys. Abbreviated Journal J. Appl. Phys.  
  Volume 87 Issue 1 Pages 502-510  
  Keywords NbN HEB mixers, nonthermal  
  Abstract We present an analysis of a diffusion-cooled hot-electron detector fabricated from clean superconducting material with low transition temperature. The distinctive feature of a clean material, i.e., material with large electron mean free path, is a relatively weak inelastic electron scattering that is not sufficient for the establishment of an elevated thermodynamic electron temperature when the detector is subjected to irradiation. We propose an athermal model of a diffusion-cooled detector that relies on suppression of the superconducting energy gap by the actual dynamic distribution of excess quasiparticles. The resistive state of the device is caused by the electric field penetrating into the superconducting bridge from metal contacts. The dependence of the penetration length on the energy gap delivers the detection mechanism. The sources of the electric noise are equilibrium fluctuations of the number of thermal quasiparticles and frequency dependent shot noise. Using material parameters typical for A1, we evaluate performance of the device in the heterodyne regime at terahertz frequencies. Estimates show that the mixer may have a noise temperature of a few quantum limits and a bandwidth of a few tens of GHz, while the required local oscillator power is in the μW range due to ineffective suppression of the energy gap by quasiparticles with high energies.  
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  ISSN 0021-8979 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1558  
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Author Smirnov, K. V.; Ptitsina, N. G.; Vakhtomin, Y. B.; Verevkin, A. A.; Gol’tsman, G. N.; Gershenzon, E. M. url  doi
openurl 
  Title Energy relaxation of two-dimensional electrons in the quantum Hall effect regime Type Journal Article
  Year 2000 Publication JETP Lett. Abbreviated Journal JETP Lett.  
  Volume 71 Issue 1 Pages 31-34  
  Keywords 2DEG, GaAs/AlGaAs heterostructures  
  Abstract The mm-wave spectroscopy with high temporal resolution is used to measure the energy relaxation times τe of 2D electrons in GaAs/AlGaAs heterostructures in magnetic fields B=0–4 T under quasi-equilibrium conditions at T=4.2 K. With increasing B, a considerable increase in τe from 0.9 to 25 ns is observed. For high B and low values of the filling factor ν, the energy relaxation rate τ −1e oscillates. The depth of these oscillations and the positions of maxima depend on the filling factor ν. For ν>5, the relaxation rate τ −1e is maximum when the Fermi level lies in the region of the localized states between the Landau levels. For lower values of ν, the relaxation rate is maximum at half-integer values of τ −1e when the Fermi level is coincident with the Landau level. The characteristic features of the dependence τ −1e (B) are explained by different contributions of the intralevel and interlevel electron-phonon transitions to the process of the energy relaxation of 2D electrons.  
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  ISSN 0021-3640 ISBN Medium  
  Area Expedition Conference  
  Notes http://jetpletters.ru/ps/899/article_13838.shtml (“Энергетическая релаксация двумерных электронов в области квантового эффекта Холла”) Approved no  
  Call Number Serial 1559  
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Author Gerecht, E.; Musante, C. F.; Zhuang, Y.; Yngvesson, K. S.; Gol’tsman, G. N.; Voronov, B. M.; Gershenzon, E. M. url  doi
openurl 
  Title NbN hot electron bolometric mixerss—a new technology for low-noise THz receivers Type Journal Article
  Year 1999 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 47 Issue 12 Pages 2519-2527  
  Keywords NbN HEB mixers  
  Abstract New advances in hot electron bolometer (HEB) mixers have recently resulted in record-low receiver noise temperatures at terahertz frequencies. We have developed quasi-optically coupled NbN HEB mixers and measured noise temperatures up to 2.24 THz, as described in this paper. We project the anticipated future performance of such receivers to have even lower noise temperature and local-oscillator power requirement as well as wider gain and noise bandwidths. We introduce a proposal for integrated focal plane arrays of HEB mixers that will further increase the detection speed of terahertz systems.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1557-9670 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1560  
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Author Il'in, K. S.; Verevkin, A. A.; Gol'tsman, G. N.; Sobolewski, R. url  doi
openurl 
  Title Infrared hot-electron NbN superconducting photodetectors for imaging applications Type Journal Article
  Year 1999 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.  
  Volume 12 Issue 11 Pages 755-758  
  Keywords NbN SSPD, SNSPD  
  Abstract We report an effective quantum efficiency of 340, responsivity >200 A W-1 (>104 V W-1) and response time of 27±5 ps at temperatures close to the superconducting transition for NbN superconducting hot-electron photodetectors (HEPs) in the near-infrared and optical ranges. Our studies were performed on a few nm thick NbN films deposited on sapphire substrates and patterned into µm-size multibridge detector structures, incorporated into a coplanar transmission line. The time-resolved photoresponse was studied by means of subpicosecond electro-optic sampling with 100 fs wide laser pulses. The quantum efficiency and responsivity studies of our photodetectors were conducted using an amplitude-modulated infrared beam, fibre-optically coupled to the device. The observed picosecond response time and the very high efficiency and sensitivity of the NbN HEPs make them an excellent choice for infrared imaging photodetectors and input optical-to-electrical transducers for superconducting digital circuits.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0953-2048 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1562  
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Author Rönnung, F.; Cherednichenko, S.; Winkler, D.; Gol'tsman, G. N. url  doi
openurl 
  Title A nanoscale YBCO mixer optically coupled with a bow tie antenna Type Journal Article
  Year 1999 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.  
  Volume 12 Issue 11 Pages 853-855  
  Keywords YBCO HTS HEB mixers  
  Abstract The bolometric response of YBa2Cu3O7-δ(YBCO) hot-electron bolometers (HEBs) to near-infrared radiation was studied. Devices were fabricated from a 50 nm thick film and had in-plane areas of 10 × 10 µm2, 2 × 0.2 µm2, 1 × 0.2µm2 and 0.5 × 0.2 µm2. We found that nonequilibrium phonons cool down more effectively for the bolometers with smaller area. For the smallest bolometer the bolometric component in the response is 10 dB less than for the largest one.  
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  Series Volume Series Issue Edition  
  ISSN 0953-2048 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1563  
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Author Gol’tsman, G. N.; Gershenzon, E. M. url  doi
openurl 
  Title Phonon-cooled hot-electron bolometric mixer: overview of recent results Type Journal Article
  Year 1999 Publication Appl. Supercond. Abbreviated Journal Appl. Supercond.  
  Volume 6 Issue 10-12 Pages 649-655  
  Keywords NbN HEB mixers  
  Abstract The paper presents an overview of recent results for NbN phonon-cooled hot electron bolometric (HEB) mixers. The noise temperature of the receivers based on both quasioptical and waveguide versions of HEB mixer has crossed the level of 1 K·GHz−1 at 430 GHz (410 K) and 600–650 GHz (480 K) and is close to this level at 820 GHz (1100 K) and 900 GHz (980 K). The gain bandwidth measured for quasioptical HEB mixer at 620 GHz reached 4 GHz and the noise temperature bandwidth was almost 8 GHz. Local oscillator power requirements are about 1 μW for mixers made by photolithography and are about 100 nW for mixers made by e-beam lithography. The studies in terahertz receivers based on HEB superconducting mixers now present a dynamic, rapidly developing field.  
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  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0964-1807 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1564  
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