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Author Gol'tsman, G. N.; Karasik, B. S.; Okunev, O. V.; Dzardanov, A. L.; Gershenzon, E. M.; Ekstrom, H.; Jacobsson, S.; Kollberg, E. url  doi
openurl 
  Title NbN hot electron superconducting mixers for 100 GHz operation Type Journal Article
  Year 1995 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 5 Issue 2 Pages 3065-3068  
  Keywords NbN HEB mixers  
  Abstract NbN is a promising superconducting material for hot-electron superconducting mixers with an IF bandwidth larger than 1 GHz. In the 1OO GHz frequency range, the following parameters were obtained for 50 /spl Aring/ thick NbN films at 4.2 K: receiver noise temperature (DSB) /spl sim/1000 K; conversion loss /spl sim/10 dB; IF bandwidth /spl sim/1 GHz; and local oscillator power /spl sim/1 /spl mu/W. An increase of the critical current of the NbN film, increased working temperature, and a better mixer matching may allow a broader IF bandwidth up to 2 GHz, reduced conversion losses down to 3-5 dB and a receiver noise temperature (DSB) down to 200-300 K.  
  Address  
  Corporate Author Thesis  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1051-8223 ISBN Medium  
  Area Expedition Conference  
  Notes About LO power required Approved no  
  Call Number Serial (up) 255  
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Author Yagubov, P.; Gol'tsman, G.; Voronov, B.; Seidman, L.; Siomash, V.; Cherednichenko, S.; Gershenzon, E. url  openurl
  Title The bandwidth of HEB mixers employing ultrathin NbN films on sapphire substrate Type Conference Article
  Year 1996 Publication Proc. 7th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 7th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 290-302  
  Keywords NbN HEB mixers, fabrication process  
  Abstract We report on some unusual features observed during fabrication of ultrathin NbN films with high Tc. The films were used to fabricate HEB mixers, which were evaluated for IF bandwidth measurements at 140 GHz. Ultrathin films were fabricated using reactive dc magnetron sputtering with a discharge current source. Reproducible parameters of the films are assured keeping constant the difference between the discharge voltage in pure argon, and in a gas mixture, for the same current. A maximum bandwidth of 4 GHz at optimal LO and dc bias was obtained for mixer chip based on NbN film 35 A thick with Tc = 11 K.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Charlottesville, Virginia, USA Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial (up) 266  
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Author Kawamura, J.; Blundell, R.; Tong, C-Y. E.; Gol'tsman, G.; Gershenzon, E.; Voronov, B.; Cherednichenko, S. url  openurl
  Title Phonon-cooled NbN HEB mixers for submillimeter wavelengths Type Conference Article
  Year 1997 Publication Proc. 8th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 8th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 23-28  
  Keywords waveguide NbN HEB mixers  
  Abstract The noise performance of receivers incorporating NbN phonon-cooled superconducting hot electron bolometric mixers is measured from 200 GHz to 900 GHz. The mixer elements are thin-film (thickness — 4 nm) NbN with —5 to 40 pm area fabricated on crystalline quartz sub- strates. The receiver noise temperature from 200 GHz to 900 GHz demonstrates no unexpected degradation with increasing frequency, being roughly TRx ,; 1-2 K The best receiver noise temperatures are 410 K (DSB) at 430 GHz, 483 K at 636 GHz, and 1150 K at 800 GHz.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial (up) 275  
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Author Cherednichenko, S.; Yagoubov, P.; Il'In, K.; Gol'tsman, G.; Gershenzon, E. url  openurl
  Title Large bandwidth of NbN phonon-cooled hot-electron bolometer mixers on sapphire substrates Type Conference Article
  Year 1997 Publication Proc. 8th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 8th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 245-257  
  Keywords NbN HEB mixers, fabrication process  
  Abstract The bandwidth of NbN phonon-cooled hot electron bolometer mixers has been systematically investigated with respect to the film thickness and film quality variation. The films, 2.5 to 10 mm thick, were fabricated on sapphire substrates using DC reactive magnetron sputtering. All devices consisted of several parallel strips, each 1 1.1 wide and 211 long, placed between Ti-Au contact pads. To measure the gain bandwidth we used two identical BWOs operating in the 120-140 GHz frequency range, one functioning as a local oscillator and the other as a signal source. The majority of the measurements were made at an ambient temperature of 4.5 K with optimal LO and DC bias. The maximum 3 dB bandwidth (about 4 GHz) was achieved for the devices made of films which were 2.5-3.5 nm thick, had a high critical temperature, and high critical current density. A theoretical analysis of bandwidth for these mixers based on the two-temperature model gives a good description of the experimental results if one assumes that the electron temperature is equal to the critical temperature.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial (up) 276  
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Author Ekstörm, H.; Kollberg, E.; Yagoubov, P.; Gol'tsman, G.; Gershenzon, E.; Yngvesson, S. url  doi
openurl 
  Title Gain and noise bandwidth of NbN hot-electron bolometric mixers Type Journal Article
  Year 1997 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 70 Issue 24 Pages 3296-3298  
  Keywords NbN HEB mixers, conversion loss, conversion gain, U-factor technique  
  Abstract We have measured the noise performance and gain bandwidth of 35 Å thin NbN hot-electron mixers integrated with spiral antennas on silicon substrate lenses at 620 GHz. The best double-sideband receiver noise temperature is less than 1300 K with a 3 dB bandwidth of ≈5 GHz. The gain bandwidth is 3.2 GHz. The mixer output noise dominated by thermal fluctuations is 50 K, and the intrinsic conversion gain is about −12 dB. Without mismatch losses and excluding the loss from the beamsplitter, we expect to achieve a receiver noise temperature of less than 700 K.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial (up) 279  
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