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Author Gol'tsman, G. N.; Karasik, B. S.; Svechnikov, S. I.; Gershenzon, E. M.; Ekström, H.; Kollberg E.
Title Noise temperature of NbN hot—electron quasioptical superconducting mixer in 200-700 GHz range Type Abstract
Year 1995 Publication Proc. 6th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 6th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 268
Keywords NbN HEB mixers, noise temperature
Abstract The electron heating effect in superconducting films is becoming very attractive for the development of THz range mixers because of the absence of frequency limitations inherent in the bolometric mechanism. However, the evidence for the spectral dependence of the position of optimal operating point has been found recently for NbN thin film devices 1.2 • The effect is presumably attributed to the variation in the absorption of radiation depending on the frequency. Since the resistive state is not spatially uniform the coupling efficiency of the mixer device with radiation can be different for frequencies larger than Zeilh and those smaller than 2Alh (d is the effective superconducting gap in the resistive state). To study the effect more thoroughly we have investigated the noise temperature of quasioptical NbN mixer device with broken hue tapered slot antenna in the frequency range 200-700 GHz. The device consists of several (5-10) parallel strips 1 jim wide and 6-7 tun thick made from NbN film on Si0 2 -Si 3 N 4 -Si membrane. The strips are connected with the gold contacts of the slot-line antenna which serves both as bias and IF leads. We used backward wave oscillators as LO sources and a standard hot/cold load technique for noise temperature measurements. The frequency dependence of noise temperature is mainly determined by two factors: frequency properties of the antenna and frequency dependence of the NbN film impedance. To separate both factors we monitored the frequency dependence of the device responsivity in the detector mode at a higher temperature within the superconducting transition where the impedance of NbN film is close to its normal resistance. In this case the impedance of the device itself is frequency independent. The experimental results will be reported at the Symposium. 1. G. Gollsman, S. Jacobsson, H. EkstrOm, B. Karasik, E. Kollberg, and E. Gershenzon, “Slot-line tapered antenna with NbN hot electron mixer for 300-360 GHz operation,” Proc of the 5th Int. Symp. on Space Terahertz Technology, pp. 209-213a, May 10-12,1994. 2. B.S. Karasik, G.N. Gol i tsman, B.M. Voronov, S.I. Svechnikov, E.M. Gershenzon, H. Ekstrom, S. Jacobsson, E. Kollberg, and K.S. Yngvesson, “Hot electron quasioptical NbN superconducting mixer,” presented at the ASC94, submitted to IEEE Trans. on Appl. Superconductivity.
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Notes Approved no
Call Number Serial 1627
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Author Ekström, H.; Karasik, B.; Kollberg, E.; Gol'tsman, G.; Gershenzon, E.
Title 350 GHz NbN hot electron bolometer mixer 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 269-283
Keywords NbN HEB mixers
Abstract Superconducting NbN hot-electron bolometer (HEB) mixer devices have been fabricated and measured at 350 GHz. The HEB is integrated with a double dipole antenna on an extended crystalline quartz hyper hemispherical substrate lens. Heterodyne measurement gave a -3 dB bandwidth, mainly determined by the electron- phonon interaction time, of about 680 and 1000 MHz for two different films with Tc = 8.5 and 11 K respectively. The measured DSB receiver noise temperature is around 3000 K at 800 MHz IF frequency. The main contribution to the output noise from the device is due to electron temperature fluctuations with the equivalent output noise temperature TFL-100 K. TH, has the same frequency dependence as the IF response. The contribution from Johnson noise is of the order of T. The RF coupling loss is estimated to be = 6 dB. The film with lower Tc, had an estimated intrinsic low-frequency conversion loss = 7 dB, while the other film had a conversion loss as high as 14 dB. The difference in intrinsic conversion loss is explained by less uniform absorption of radiation. Measurements of the small signal impedance shows a transition of the output impedance from the DC differential resistance Rd=dV/dI in the low frequency limit to the DC resistance R 0 =Uoff 0 in the bias point for frequencies above 3 GHz. We judge that the optimum shape of the IV-characteristic is more easily obtained at THz frequencies where the main restriction in performance should come from problems with the RF coupling.
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Notes Approved no
Call Number Serial 1628
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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.
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 Voronov, B. M.; Gershenzon, E. M.; Gol'tsman, G. N.; Gubkina, T. O.; Semash, V. D.
Title Superconductive properties of ultrathin NbN films on different substrates Type Journal Article
Year 1994 Publication Sverkhprovodimost': Fizika, Khimiya, Tekhnika Abbreviated Journal Sverkhprovodimost': Fizika, Khimiya, Tekhnika
Volume 7 Issue 6 Pages 1097-1102
Keywords NbN films
Abstract A study was made on dependence of surface resistance, critical temperature and width of superconducting transition on application temperature and thickness of NbN films, which varied within the range of 3-10 nm. Plates of sapphire, fused and monocrystalline quartz, MgO, as well as Si and silicon oxide were used as substrates. NbN films with 160 μθ·cm specific resistance and 16.5 K (Tc) critical temperature were obtained on sapphire substrates. Intensive growth of ΔTc was noted for films, applied on fused quartz, with increase of precipitation temperature. This is explained by occurrence of high tensile stresses in NbN films, caused by sufficient difference of thermal coefficients of expansion of NbN and quartz.
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Publisher Place of Publication Editor
Language Russian Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0131-5366 ISBN Medium
Area Expedition Conference
Notes Сверхпроводниковые свойства ультратонких пленок NbN на различных подложках Approved no
Call Number Serial 1631
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Zorin, M. A.; Karasik, B. S.; Trifonov, V. A.
Title Nonequilibrium and bolometric response of YBaCuO films in a resistive state to infrared low intensity radiation Type Conference Article
Year 1994 Publication Council on Low-temp. Phys. Abbreviated Journal Council on Low-temp. Phys.
Volume Issue Pages 82-83
Keywords YBCO HTS HEB
Abstract
Address Dubna
Corporate Author Thesis
Publisher Place of Publication Editor
Language Russian Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN Medium
Area Expedition Conference Joint Inst. for Nuclear Research, Dubna (Russian Federation); 296 p; 1994; p. 82-83; 30. Conference on low-temperature physics; 30. Soveshchanie po fizike nizkikh temperatur; Dubna (Russian Federation); 6-8 Sep 1994
Notes Неравновесный и болометрический отклик YBaCuO пленок в резиотивном состоянии на инфракрасное лазерное излучение малой интенсивности Approved no
Call Number Serial 1632
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Author Gol'tsman, G.; Jacobsson, S.; Ekstrom, H.; Karasik, B.; Kollberg, E.; Gershenzon, E.
Title Slot-line tapered antenna with NbN hot electron mixer for 300-360 GHz operation Type Conference Article
Year 1994 Publication Proc. 5th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 5th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 209-213a
Keywords NbN HEB mixers
Abstract NbN hot-electron mixers combined with slot-line tapered antennas on Si wdnitride membranes had been fabricated. Several strips of 1 gm wide and 5 tan long made from 100 A NbN film are inserted into the slot antenna. IV-curves under local oscillator power in 300-350 GHz frequency range and conversion gain dependencies on intermediate fre- quency in the 0.1-1 GHz range are measured and compared with that for 100 GHz frequency band. Our results show that pumped IV-curves and intermediate frequency bands are different for 100 GHz and 300 GHz frequency ranges. The interpretation exploits the fact that for the lowest radiation frequency the superconducting energy gap is larger than the radiation quantum energy while they are comparable at the higher frequency. Tha results show that such mixers have good perspectives for terahertz receiving technology.
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Notes Approved no
Call Number Serial 1643
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Author 0kunev, 0.; Dzardanov, A.; Ekstrom, H.; Jacobsson, S.; Kollberg, E.; Gol'tsman, G.; Gershenzon, E.
Title NbN hot electron waveguide mixer for 100 GHz operation Type Conference Article
Year 1994 Publication Proc. 5th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 5th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 214-224
Keywords waveguide NbN HEB mixers
Abstract NbN is a promising superconducting material used to develope hot- electron superconducting mixers with an IF bandwidth over 1 GHz. In the 100 GHz frequency range, the following parameters were obtained for NbN films 50 A thick: the noise temperature of the receiver (DSB) 1000 K; the conversion losses 10 d13, the IF bandwidth 1 GHz; the local oscillator power 1 /LW. An increase of NbN film thickness up to 80-100 A and increase of working temperature up to 7-8 K, and a better mixer matching may allow to broader the IF band up to 3 Gllz, to reduce the conversion losses down to 3-5 dB and the noise tempera- ture down to 200-300 K.
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Notes Approved no
Call Number Serial 1644
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Author Gershenzon, E. M.; Gol'tsman, G. N.
Title Hot electron superconductive mixers Type Conference Article
Year 1993 Publication Proc. 4th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 4th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 618-622
Keywords HEB mixers
Abstract
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Notes Approved no
Call Number Serial 1656
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Author Gol'tsman, G. N.; Elant'iev, A. I.; Karasik, B. S.; Gershenzon, E. M.
Title Antenna – coupled superconducting electron-heating bolometer Type Conference Article
Year 1993 Publication Proc. 4th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 4th Int. Symp. Space Terahertz Technol.
Volume Issue Pages 623-628
Keywords HEB
Abstract We propose a novel antenna-coupled superconducting bolometer based on electron-heating in the resistive state. A short narrow ultrathin super- conducting film strip (sized approximately 4x1x0.01 pm 3 ), which is in good thermal contact with the thermostat, serves as a resistive load for infrared or submillimeter current. In contrast to conventional isothermal super- conducting bolometers electron-heating ones can have a higher sensitivity which grows when filni. thickness is reduced. Response time of electron- heating bolometer does not depend on heat transfer from the film to the enviroment. To calculate the sensitivity (NEP), we have used experimental data on wideband Al, Nb and NbN bolometers which have the same un- derlying physical mechanism. The bolom.eters have been made in the form of a structure composed of a number of long narrow strips. The values of for Al, NEP have been found to be 1.5 . 113 -16 1 140 -15 ) and 2 . 10 – 14werT,-1/2 – Nb and NbN respectively. In the paper, the prospects are also discussed of improving the picosecond YBaCuO detector, developed recently. NEP value of the detector, if combined with a microantenna, can reach the order of 10- •ilz-v2.
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Area Expedition Conference
Notes Approved no
Call Number Serial 1657
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Author Semenov, A. D.; Sergeev, A. V.; Kouminov, P.; Goghidze, I. G.; Heusinger, M. A.; Nebosis, R. S.; Gol'tsman, G. N.; Gershenzon, E. M.; Renk, K. F.
Title Transparency of YBCO film/substrate interfaces for thermal phonons determined by photoresponse measurements Type Conference Article
Year 1993 Publication Proc. 1st European Conf. on Appl. Supercond. Abbreviated Journal Proc. 1st European Conf. on Appl. Supercond.
Volume 2 Issue Pages 1443-1446
Keywords YBCO HTS detectors
Abstract Direct measurements of the thermal boundary resistance were performed by means of the stationary method. In this approach the temperature of an electrically heated film is controlled by its dc resistance while an additional film on the same substrate is used as a thermometer monitoring substrate temperature. The temperature field in the substrate is then calculated to deduce the Kapitza temperature step at the interface between the heated strip and the substrate. The main statement of all afore-said papers is that experimental values of the thermal boundary resistance are too large to be explained by the acoustic mismatch model. In this paper we investigate transparency of YBaCuO film/substrate interfaces for thermal phonons by means of photoresponse measurements. We show that our data are in reasonable agreement with the acoustic mismatch theory.
Address
Corporate Author Thesis
Publisher Place of Publication Editor Freyhardt, H. C.
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN ISBN 3-88355-197-X Medium
Area Expedition Conference 1st European conference on applied superconductivity
Notes Approved no
Call Number Serial 1661
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