|
|
Huebers, H. - W., Semenov, A., Richter, H., Birk, M., Krocka, M., Mair, U., et al. (2003). Superconducting hot electron bolometer as mixer for far-infrared heterodyne receivers. In T. G. Phillips, & J. Zmuidzinas (Eds.), Proc. SPIE (Vol. 4855, pp. 395–401). Presented at the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference, 4855. Tucson, USA: SPIE.
Abstract: Heterodyne receivers for applications in astronomy need quantum limited sensitivity. In instruments which are currently under development for SOFIA or Herschel superconducting hot electron bolometers (HEB) will be used to achieve this goal at frequencies above 1.4 THz. We present results of the development of a phonon-cooled NbN HEB mixer for GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be flown aboard SOFIA. The mixer is a small superconducting bridge incorporated in a planar feed antenna and a hyperhemispherical lens. Mixers with logarithmic-spiral and double-slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 17 dB. The response of the mixer was linear up to 400 K load temperature. The performance was verified by measuring an emission line of methanol at 2.5 THz. The measured linewidth is in good agreement with the linewidth deduced from pressure broadening measurements at millimeter wavelength. The results demonstrate that the NbN HEB is very well suited as a mixer for far-infrared heterodyne receivers.
|
|
|
|
Zhang, J., Pearlman, A., Slysz, W., Verevkin, A., Sobolewski, R., Wilsher, K., et al. (2003). A superconducting single-photon detector for CMOS IC probing. In Proc. 16-th LEOS (Vol. 2, pp. 602–603).
Abstract: In this paper, a novel, time-resolved, NbN-based, superconducting single-photon detector (SSPD) has been developed for probing CMOS integrated circuits (ICs) using photon emission timing analysis (PETA).
|
|
|
|
Meledin, D., Tong, C. Y. - E., Blundell, R., Kaurova, N., Smirnov, K., Voronov, B., et al. (2003). Study of the IF bandwidth of NbN HEB mixers based on crystalline quartz substrate with an MgO buffer layer. IEEE Trans. Appl. Supercond., 13(2), 164–167.
Abstract: In this paper, we present the results of IF bandwidth measurements on 3-4 nm thick NbN hot electron bolometer waveguide mixers, which have been fabricated on a 200-nm thick MgO buffer layer deposited on a crystalline quartz substrate. The 3-dB IF bandwidth, measured at an LO frequency of 0.81 THz, is 3.7 GHz at the optimal bias point for low noise receiver operation. We have also made measurements of the IF dynamic impedance, which allow us to evaluate the intrinsic electron temperature relaxation time and self-heating parameters at different bias conditions.
|
|
|
|
van't Klooster, C. G. M., Parshin, V. V., & Myasnikova, S. E. (2003). Reflectivity of antenna reflectors: measurements at frequencies between 110 and 200 GHz. In Proc. Antennas and propagation society international symposium (Vol. 3, pp. 528–531).
Abstract: It is imperative to test the mechanical, electrical and thermal-optical properties of MM and sub-MM reflector antennas. Electrical, thermal and optical properties are very important and high-accurate measurements lead, obviously, to more accurate results in applications. This paper deals with measurement of electrical reflectivity in the range 110-200 GHz. Reflectivity has been measured for a number of samples, which represent materials used in reflector antennas. Both metal samples and carbon-fibre samples were tested in a dedicated facility available for this purpose at the Applied Physics Institute in Nizhny Novgorod (IAP). The test facility is shortly discussed, with techniques for data extraction. Calibration is done with high quality silver coated mirrors and aluminium control samples. Accurate results have been derived with indicative interesting results.
|
|
|
|
Vakhtomin, Y. B., Finkel, M. I., Antipov, S. V., Smirnov, K. V., Kaurova, N. S., Drakinskii, V. N., et al. (2003). The gain bandwidth of mixers based on the electron heating effect in an ultrathin NbN film on a Si substrate with a buffer MgO layer. J. of communications technol. & electronics, 48(6), 671–675.
Abstract: Measurements of the intermediate frequency band 900 GHz of mixers based on the electron heating effect (EHE) in 2-nm- and 3.5-nm-thick superconducting NbN films sputtered on MgO and Si substrates with buffer MgO layers are presented. A 2-nm-thick superconducting NbN film with a critical temperature of 9.2 K has been obtained for the first time using a buffer MgO layer.
|
|
|
|
Baselmans, J. J. A., Hajenius, M., Gao, J. R., Klapwijk, T. M., de Korte, P. A. J., Voronov, B., et al. (2003). Noise performance of NbN hot electron bolometer mixers at 2.5 THz and its dependence on the contact resistance. In Proc. 14th Int. Symp. Space Terahertz Technol. (pp. 11–19).
Abstract: NbN hot electron bolometer mixers (HEBM) are at this moment the best heterodyne receivers for frequencies above 1 Thz. However, the fabrication procedure of these devices is such that the quality of the interface between the NbN superconducting film and the contact structure is not under good control. The result is a low transparency interface between the bolometer itself and the contact/antenna structure. In this paper we report a detailed experimental study on a novel idea to increase the transparency of this interface. This leads to a record sensitivity and more reproducible performance. We compare identical bolometers, coupled with a spiral antenna, with different NbN bolometer-contact pad interfaces. We find that cleaning the NbN interface alone results in an increase in the noise temperature. However, cleaning the NbN interface and adding a thin additional superconductor prior to the gold contact deposition improves the noise temperature of the HEBm with more than a factor of 2. A device with a contact pad on top of an in-situ cleaned NbN film consisting of 10 nm of NbTiN and 40 nm of gold has a DSB noise temperature of 1050 K at 2.5 THz.
|
|
|
|
Cherednichenko, S., Khosropanah, P., Adam, A., Merkel, H. F., Kollberg, E. L., Loudkov, D., et al. (2003). 1.4- to 1.7-THz NbN hot-electron bolometer mixer for the Herschel space observatory. In T. G. Phillips, & J. Zmuidzinas (Eds.), Proc. SPIE (Vol. 4855, pp. 361–370). SPIE.
Abstract: NbN hot- electron bolometer mixers have reached the level of 10hv/k in terms of the input noise temperature with the noise bandwidth of 4-6 GHz from subMM band up to 2.5 THz. In this paper we discuss the major characteristics of this kind of receiver, i.e. the gain and the noise bandwidth, the noise temperature in a wide RF band, bias regimes and optimisation of RF coupling to the quasioptical mixer. We present the status of the development of the mixer for Band 6 Low for Herschel Telescope.
|
|
|
|
Hajenius, M., Baselmans, J. J. A., Gao, J. R., Klapwijk, T. M., de Korte, P. A. J., Voronov, B., et al. (2003). Improved NbN phonon cooled hot electron bolometer mixers. In Proc. 14th Int. Symp. Space Terahertz Technol. (pp. 413–423). Tucson, USA.
Abstract: NbN phonon-cooled hot electron bolometer mixers (HEBs) have been realized with negligible contact resistance to Au pads. By adding either a 5 nm Nb or a 10 nm NbTiN layer between the Au and NbN, to preserve superconductivity in the NbN under the Au contact pad, superior noise temperatures have been obtained. Using DC I,V curves and resistive transitions in combination with process parameters we analyze the nature of these improved devices and determine interface transparencies.
|
|
|
|
Smirnov, K. V., Vachtomin, Y. B., Antipov, S. V., Maslennikov, S. N., Kaurova, N. S., Drakinsky, V. N., et al. (2003). Noise and gain performance of spiral antenna coupled HEB mixers at 0.7 THz and 2.5 THz. In Proc. 14th Int. Symp. Space Terahertz Technol. (pp. 405–412).
Abstract: Noise and gain performance of hot electron bolometer (HEB) mixers based on ultrathin superconducting NbN films integrated with a spiral antenna was studied. The noise temperature measurements for two samples with different active area of 3 p.m x 0.24 .tni and 1.3 1..tm x 0.12 1.tm were performed at frequencies 0.7 THz and 2.5 THz. The best receiver noise temperatures 370 K and 1600 K, respectively, have been found at these frequencies. The influence of contact resistance between the superconductor and the antenna terminals on the noise temperature of HEB is discussed. The noise and gain bandwidth of 5GHz and 4.2 GHz, respectively, are demonstrated for similar HEB mixer at 0.75 THz.
|
|
|
|
Zhang, J., Pearlman, A., Slysz, W., Verevkin, A., Sobolewski, R., Okunev, O., et al. (2003). Infrared picosecond superconducting single-photon detectors for CMOS circuit testing. In CLEO/QELS (Cmv4). Optical Society of America.
Abstract: Novel, NbN superconducting single-photon detectors have been developed for ultrafast, high quantum efficiency detection of single quanta of infrared radiation. Our devices have been successfully implemented in a commercial VLSI CMOS circuit testing system.
|
|
|
|
Myasnikova, S. E., Parshin, V. V., van't Klooster, K., & Valsecchi, G. (2003). Reflectivity of antenna and mirrors reflectors at 110 and 200 GHz. In Proc. 4th international conference on antenna theory and techniques (Vol. 2, pp. 624–627).
Abstract: Reflectivity (reflection loss) investigations of nickel samples with different types of surface finish, with and without rhodium coating, have been carried out in the 110-200 GHz frequency range on an installation developed in the Applied Physics Institute of Russia. The reflectivity measurements of high quality silver coated and gold coated mirrors are also presented. The reflectivity (reflection loss) investigations of some carbon fibre samples with and without aluminium coating have been made. Results are interesting, in view of the anisotropy of the carbon fibre material.
|
|
|
|
Zhang, J., Boiadjieva, N., Chulkova, G., Deslandes, H., Gol'tsman, G. N., Korneev, A., et al. (2003). Noninvasive CMOS circuit testing with NbN superconducting single-photon detectors. Electron. Lett., 39(14), 1086–1088.
Abstract: The 3.5 nm thick-film, meander-structured NbN superconducting single-photon detectors have been implemented in the CMOS circuit-testing system based on the detection of near-infrared photon emission from switching transistors and have significantly improved the performance of the system. Photon emissions from both p- and n-MOS transistors have been observed.
|
|
|
|
Khosropanah, P. (2003). NbN and NbTiN hot electron bolometer THz mixers. Ph.D. thesis, Chalmers University of Technology, Göteborg.
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.
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
|
|
|
|
Aberle, N., & Witte, U. (2003). Deep-sea macrofauna exposed to a simulated sedimentation event in the abyssal NE Atlantic: in situ pulse-chase experiments using 13C-labelled phytodetritus. Mar Ecol Prog Ser, 251, 37–47.
Abstract: Tracer experiments with 13C-labelled diatoms Thalassiosira rotula (Bacillariophycea, 98% 13C-labelled) were conducted at the Porcupine Abyssal Plain (PAP) in the NE Atlantic (BENGAL Station; 48<b0>50'N, 16<b0>30'W, 4850 m depth) during May/June 2000. In situ enrichment experiments were carried out using deep-sea benthic chamber landers: within the chambers a spring bloom was simulated and the fate of this food-pulse within the abyssal macrobenthic community was followed. In focus was the role of different macrofauna taxa and their vertical distribution within the sediment column in consuming and reworking the freshly deposited material. T. rotula is one of the most abundant pelagic diatoms in the NE Atlantic and therefore 0.2 g of freeze dried T. rotula, equivalent to 1 g algal C m-2 yr-1, was injected into each incubation chamber. Three different incubation times of 2.5, 8 and 23 d were chosen in order to follow the uptake of 13C-labelled phytodetritus by macrofauna. After only 2.5 d, 77% of all macrofauna organisms showed tracer uptake. After 23 d the highest degree of enrichment was measured and 95% of the individuals had taken up 13C from the introduced algal material. In addition to that a downward transport of organic matter was observed, even though the mixing was not very intense. The initial processing of carbon was dominated by polychaetes that made up a percentage of 52% of total macrofauna. In general macrofauna organisms that lived close to the sediment surface had higher access to the simulated food-pulse, confirming the hypothesis that individuals close to the sediment surface have the strongest impact on the decomposition of phytodetritus. In our study we observed only modest vertical entrainment of 13C tracers into the sediment. With regard to contradictory results from former 13C-enrichment experiments in bathyal regions, compared to results from our study site in the abyssal plain, we thus propose pronounced differences in feeding strategies between macrofauna communities from continental margins and abyssal plains.
|
|
|
|
Semenov, A., Engel, A., Il'in, K., Gol'tsman, G., Siegel, M., & Hübers, H. - W. (2003). Ultimate performance of a superconducting quantum detector. Eur. Phys. J. Appl. Phys., 21(3), 171–178.
Abstract: We analyze the ultimate performance of a superconducting quantum detector in order to meet requirements for applications in near-infrared astronomy and X-ray spectroscopy. The detector exploits a combined detection mechanism, in which avalanche quasiparticle multiplication and the supercurrent jointly produce a voltage response to a single absorbed photon via successive formation of a photon-induced and a current-induced normal hotspot in a narrow superconducting strip. The response time of the detector should increase with the photon energy providing energy resolution. Depending on the superconducting material and operation conditions, the cut-off wavelength for the single-photon detection regime varies from infrared waves to visible light. We simulated the performance of the background-limited infrared direct detector and X-ray photon counter utilizing the above mechanism. Low dark count rate and intrinsic low-frequency cut-off allow for realizing a background limited noise equivalent power of 10−20 W Hz−1/2 for a far-infrared direct detector exposed to 4-K background radiation. At low temperatures, the intrinsic response time of the counter is rather determined by diffusion of nonequilibrium electrons than by the rate of energy transfer to phonons. Therefore, thermal fluctuations do not hamper energy resolution of the X-ray photon counter that should be better than 10−3 for 6-keV photons. Comparison of new data obtained with a Nb based detector and previously reported results on NbN quantum detectors support our estimates of ultimate detector performance.
|
|
