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Author Shurakov, Alexander; Maslennikov, Sergey; Tong, Cheuk-yu E.; Gol’tsman, Gregory url  openurl
  Title Performance of an HEB direct detector utilizing a microwave reflection readout scheme Type Conference Article
  Year 2015 Publication Proc. 26th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 26th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 36  
  Keywords HEB detector  
  Abstract We report the results of our study on the performance of a hot electron bolometric (HEB) direct detector, operated by a microwave pump. The HEB devices used in this work were made from NbN thin film deposited on high resistivity silicon with an in-situ fabrication process. The experimental setup employed is similar to the one described in [1]. The detector chips were glued to a silicon lens clamped to a copper holder mounted on the cold plate of a liquid helium cryostat. Thermal link between the lens and the holder was maintained by a thin indium shim. The HEBs were operated at a bath temperature of about 4.4 K. Conventional phonon pump, commonly realized by raising the bath temperature of the detector, was substituted by a microwave one. In this case, a CW microwave signal is injected to the device through a directional coupler connected directly to the detector holder. The power incident on the HEB device was typically 1-2 μW, and the pump frequency was in the range of 0.5-1.5 GHz. The signal sources were 2 black bodies held at temperatures of 295 K and 77 K. A chopper wheel placed in front of the cryostat window switched the input to the detector between the 2 sources. A modulation frequency of several kilohertz was chosen in order to reduce the effects of the HEB’s flicker noise. A cold mesh filter was used to define the input bandwidth of the detector. The reflected microwave signal from the HEB device was fed into a low noise amplifier, the output of which is connected to a room temperature Schottky microwave power detector. This Schottky detector, in conjunction with a lock-in amplifier, demodulated the input signal modulation from the copper wheel. As the input load was switched, the impedance of the HEB device at the microwave pump frequency also changed in response to the incident signal power variation. Therefore the reflected microwave power follows the incident signal modulation. The derived responsivity from this detection system nicely correlates with the HEB impedance. In order to provide a quantitative description of the impedance variation of the HEB device and the impact of a microwave pump, we have numerically solved the heat balance equations written for the NbN bridge and its surrounding thermal heat sink [2]. Our model also accounts for the impact of the operating frequency of the detector because of non-uniform absorption of low-frequency photons across the NbN bridge [3]. In our measurements we varied the signal source wavelength from 2 mm down to near infrared range, and hence we indirectly performed the impedance measurements at frequencies below, around and far beyond the superconducting gap. Preliminary results show good agreement between the experiment and theoretical prediction. Further measurements are still in progress. [1] A. Shurakov et al., “A Microwave Reflection Readout Scheme for Hot Electron Bolometric Direct Detector”, to appear in IEEE Trans. THz Sci. Tech., 2015. [2] S. Maslennikov, “RF heating efficiency of the terahertz superconducting hot-electron bolometer”, http://arxiv.org/pdf/1404.5276v5.pdf, 2014. [3] W. Miao et al., “Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges”, Appl. Phys. Let., 104, 052605, 2014.  
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  Notes Approved no  
  Call Number Serial 1158  
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Author Shurakov, Alexander; Tong, Cheuk-yu E.; Blundell, Raymond; Gol’tsman, Gregory url  openurl
  Title A microwave pumped HEB direct detector using a homodyne readout scheme Type Abstract
  Year 2014 Publication Proc. 25th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 25th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 129  
  Keywords waveguide NbN HEB detector, NEP  
  Abstract We report the results of our study on the noise performance of a fast THz detector based on the repurpose of hot electron bolometer mixer (HEB). Instead of operating with an elevated bath temperature, microwave power is injected into the HEB device, which enhances the sensitivity of the detector and at the same time provide a mechanism for reading out impedance changes of the device induced by the modulated incident THz radiation [1]. We have demonstrated an improvement of the detector’s optical noise equivalent power (NEP). Furthermore, by introducing a homodyne readout scheme based on a room temperature microwave mixer, the dynamic range of the detector is increased. The HEB devices used in this work were made of 4 nm thick NbN film. The detector chips were installed into a waveguide mixer block fitted with a corrugated horn, mounted on the cold plate of a liquid helium cryostat. The HEBs were operated at a bath temperature of 4.2 K. The signal beam was terminated on black bodies at ambient and liquid nitrogen temperatures. A chopper wheel placed in front of the cryostat window operating at a frequency of 1.48 kHz modulated the input load temperature of the detector. A cold mesh filter, centered at 830 GHz, was used to define the input signal power bandwidth. Microwave was injected through a broadband directional coupler inside the cryostat. Our experiments were mostly conducted at a pump frequency of 1.5 GHz. The reflected microwave power from the HEB device was fed into a cryogenic low noise amplifier (LNA). The output of the LNA was connected to the RF input port of a room temperature microwave mixer, which beat the reflected signal from the HEB using a copy of the original 1.5 GHz injection signal in a homodyne demodulation scheme. The amplitude of the detected power was measured by a lock-in amplifier, which was synchronized to the chopper frequency. Preliminary results yield an optical NEP of ~1 pW/ Hz 1/2 which corresponds to an improvement of a factor of 3 compared to [1], driven mainly by a lowering of the system noise floor. The dynamic range was also increased by similar amount. References 1. A. Shurakov et al. “A Microwave Pumped Hot Electron Bolometric Direct Detector,” submitted on Oct 18, 2013 to Appl. Phys. Let.  
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  Notes Approved no  
  Call Number Serial 1365  
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Author Gerecht, E.; Musante, C. F.; Schuch, R.; Lutz, C. R.; Jr.; Yngvesson, K. S.; Mueller, E. R.; Waldivian, J.; Gol'tsman, G. N.; Voronov, B. M.; Gershenzon, E. M. url  openurl
  Title Hot electron detection and mixing experiments in NbN at 119 micrometer wavelength Type Conference Article
  Year 1995 Publication Proc. 6th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 6th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 284-293  
  Keywords NbN HEB mixers, detectors  
  Abstract We have performed preliminary experiments with the goal of demonstrating a Hot Electron Bolometric (HEB) mixer for a 119 micrometer wavelength (2.5 THz). We have chosen a NbN device of size 700 x 350 micrometers. This device can easily be coupled to a laser LO source, which is advantageous for performing a prototype experiment. The relatively large size of the device means that the LO power required is in the mW range; this power can be easily obtained from a THz laser source. We have measured the amount of laser power actually absorbed in the device, and from this have estimated the best optical coupling loss to be about 10 di . We are developing methods for improving the optical coupling further. Preliminary measurements of the response of the device to a chopped black-body have not yet resulted in a measured receiver noise temperature. We expect to be able to complete this measurement in the near future.  
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  Notes Approved no  
  Call Number Serial 1629  
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Author Gershenzon, E. M.; Goltsman, G.; Orlova, S.; Ptitsina, N.; Gurvich, Y. url  openurl
  Title Germanium hot-electron narrow-band detector Type Journal Article
  Year 1971 Publication Sov. Radio Engineering And Electronic Physics Abbreviated Journal Sov. Radio Engineering And Electronic Physics  
  Volume 16 Issue 8 Pages 1346  
  Keywords Ge HEB detectors  
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  Publisher Scripps Clinic Res Foundation 476 Prospect St, La Jolla, Ca 92037 Place of Publication Editor  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1741  
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Author Dube, I.; Jiménez, D.; Fedorov, G.; Boyd, A.; Gayduchenko, I.; Paranjape, M.; Barbara, P. url  doi
openurl 
  Title Understanding the electrical response and sensing mechanism of carbon-nanotube-based gas sensors Type Journal Article
  Year 2015 Publication Carbon Abbreviated Journal Carbon  
  Volume 87 Issue Pages 330-337  
  Keywords carbon nanotubes, CNT detectors, field effect transistors, FET  
  Abstract Gas sensors based on carbon nanotube field effect transistors (CNFETs) have outstanding sensitivity compared to existing technologies. However, the lack of understanding of the sensing mechanism has greatly hindered progress on calibration standards and customization of these nano-sensors. Calibration requires identifying fundamental transistor parameters and establishing how they vary in the presence of a gas. This work focuses on modeling the electrical response of CNTFETs in the presence of oxidizing (NO2) and reducing (NH3) gases and determining how the transistor characteristics are affected by gas-induced changes of contact properties, such as the Schottky barrier height and width, and by the doping level of the nanotube. From the theoretical fits of the experimental transfer characteristics at different concentrations of NO2 and NH3, we find that the CNTFET response can be modeled by introducing changes in the Schottky barrier height. These changes are directly related to the changes in the metal work function of the electrodes that we determine experimentally, independently, with a Kelvin probe. Our analysis yields a direct correlation between the ON – current and the changes in the electrode metal work function. Doping due to molecules adsorbed at the carbon-nanotube/metal interface also affects the transfer characteristics.  
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  ISSN 0008-6223 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1778  
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Gogidze, I. G.; Semenov, A. D.; Sergeev, A. V. url  doi
openurl 
  Title Processes of electron-phonon interaction in thin YBaCuO films Type Journal Article
  Year 1991 Publication Phys. C: Supercond. Abbreviated Journal Phys. C: Supercond.  
  Volume 185-189 Issue Pages 1371-1372  
  Keywords YBCO HTS detectors  
  Abstract The ultrafast voltage response of YBaCuO films to laser radiation is studied and compared with previously investigated quasiparicles response to radiation of submillimeter wavelength range. Voltage shift under the visible light radiation has two components. Picosecond response realized as suppression superconductivity by nonequilibrium excess quasiparticles, response time is determined by quasiparticles recombination rate. Nanosecond response is probably due to bolometric effect.  
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  Series Volume Series Issue Edition  
  ISSN 0921-4534 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1676  
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Author Bespalov, A.V.; Gol'tsman, G.N.; Semenov, A.D.; Renk, K.F. url  doi
openurl 
  Title Determination of the far-infrared emission characteristic of a cyclotron p-germanium laser by use of a superconducting Nb detector Type Journal Article
  Year 1991 Publication Solid State Communications Abbreviated Journal Solid State Communications  
  Volume 80 Issue 7 Pages 503-506  
  Keywords Nb detector, applications  
  Abstract We studied the far-infrared emission characteristics of a cyclotron p-germanium laser using a broad-band superconducting Nb film detector. For magnetic fields between ∼25 kOe and ∼50 kOe, emission in a frequency range from ∼50 cm-1 to ∼100 cm-1 with maximum intensity around 90 cm-1 was obtained. We determined, for fixed magnetic fields, electric field dependences of the emission intensity taking into account that the total electric field is a sum of the applied and the Hall electric field. An analysis of the emission intensity characteristic gives evidence that transitions between the two lowest Landau levels of light holes are responsible for the laser action.  
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  Series Volume Series Issue Edition  
  ISSN 0038-1098 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1677  
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Semenov, A. D.; Sergeev, A. V. url  doi
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  Title Mechanism of picosecond response of granular YBaCuO films to electromagnetic radiation Type Journal Article
  Year 1990 Publication Solid State Communications Abbreviated Journal Solid State Communications  
  Volume 76 Issue 4 Pages 493-497  
  Keywords YBCO HTS detectors  
  Abstract The ultrafast mechanisms of radiation detection in granular YBaCuO films are studied in the wide wavelength range from millimeter to near infrared. With the rise of radiation frequency the Josephson detection at the grain boundary weak links is replaced by electron heating into the grains. This change occurs in the submillimeter wavelength range. Electron-phonon relaxation time τeph is determined by direct measurements and analyses quasistationary electron heating. Temperature dependence of τeph at T ≤ 40 K was found to be τeph ∼ T−1. The results show that detectors with the response time of few picoseconds at nitrogen temperature are attainable.  
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  ISSN 0038-1098 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1685  
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Author Heusinger, M. A.; Nebosis,R. S.; Schatz, W.; Renk, K. F.; Gol’tsman, G. N.; Karasik, B. S.; Semenov, A. D.; Gershenzon, E. M. url  doi
openurl 
  Title Temperature dependence of bolometric and non-bolometric photoresponse of a structured YBa2Cu3O7-δ thin film Type Conference Article
  Year 1993 Publication Phonon Scattering in Condensed Matter VII. Springer Series in Solid-State Sciences Abbreviated Journal Phonon Scattering in Condensed Matter VII. Springer Series in Solid-State Sciences  
  Volume 112 Issue Pages 193-195  
  Keywords YBCO HTS detectors  
  Abstract We investigated the temperature dependence of the transient voltage photoresponse of a current biased structured YBa2Cu3O7−δ thin film in its transition temperature region, around 79 K. Both, picosecond nonbolometric and nanosecond bolometric response to ultrashort far-infrared laser pulses were found for frequencies between 25 cm−1 and 215 cm−1. We will discuss optimum conditions for radiation detection and present an analysis of the dynamical behaviour of excited high T c thin films.  
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  Publisher Place of Publication Editor Meissner, M.; Pohl, R. O.  
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  Area Expedition Conference Seventh International Conference, Cornell University, Ithaca, New York, August 3-7, 1992  
  Notes Approved no  
  Call Number Serial 1663  
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Author Gol’tsman, G. N.; Semenov, A. D.; Sergeev, A. V.; Aksaev, E. E.; Gogidze, I. G.; Gershenzon, E. M. url  doi
openurl 
  Title Electron-phonon interaction in thin YBaCuO films and fast detectors Type Conference Article
  Year 1993 Publication Phonon Scattering in Condensed Matter VII. Springer Series in Solid-State Sciences Abbreviated Journal Phonon Scattering in Condensed Matter VII. Springer Series in Solid-State Sciences  
  Volume 112 Issue Pages 184-185  
  Keywords YBCO HTS detectors  
  Abstract The thin. YBaCuO film response to laser and submillimeter radiation demonstrates the picosecond nonequilibrium peak on the nanosecond bolometric background. Experimental data give an evidence for the spectral dependence of picosecond photoresponse probably due to a poor efficiency of electron multiplication processes. Presented results prove an availability of fast YBaCuO thin film detector.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor Meissner, M.; Pohl, R. O.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
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  ISSN ISBN Medium  
  Area Expedition Conference Seventh International Conference, Cornell University, Ithaca, New York, August 3-7, 1992  
  Notes Approved no  
  Call Number Serial 1662  
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