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Ozhegov, R. V., Gorshkov, K. N., Smirnov, K. V., Gol’tsman, G. N., Filippenko, L. V., & Koshelets, V. P. (2010). Terahertz imaging system based on superconducting integrated receiver. In Proc. 2-nd Int. Conf. Terahertz and Microwave radiation: Generation, Detection and Applications (pp. 20–22).
Abstract: The development of terahertz imaging instruments for security systems is on the cutting edge of terahertz technology. We are developing a THz imaging system based on a superconducting integrated receiver (SIR). An SIR is a new type of heterodyne receiver based on an SIS mixer integrated with a flux-flow oscillator (FFO) and a harmonic mixer which is used for phase-locking the FFO. Developing an array of SIRs would allow obtaining amplitude and phase characteristics of incident radiation in the plane of the receiver. Employing an SIR in an imaging system means building an entirely new instrument with many advantages compare to traditional systems: i) high temperature resolution, comparable to the best results for incoherent receivers; ii) high spectral resolution allowing spectral analysis of various substances; iii) the local oscillator frequency can be varied to obtain images at different frequencies, effectively providing “color” images; iv) since a heterodyne receiver preserves the phase of the radiation, it is possible to construct 3D images. The paper presents a prototype THz imaging system using an 1 pixel SIR. We have studied the dependence of the noise equivalent temperature difference (NETD) on the integration time and also possible ways of achieving best possible sensitivity. An NETD of 13 mK was obtained with an integration time of 1 sec a detection bandwidth of 4 GHz at a local oscillator frequency of 520 GHz. An important advantage of an FFO is its wide operation range: 300-700 GHz.
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Dieleman, P. (1998). Fundamental limitations of THz niobium and niobiumnitride SIS mixers. Ph.D. thesis, , Rijksuniversiteit, Groningen.
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Shitov, S. V., Inatani, J., Shan, W. - L., Takeda, M., Wang, Z., Uvarov, A. V., et al. (2008). Measurement of emissivity of the ALMA antenna panel at 840 GHz using NbN-based heterodyne SIS receiver. In Proc. 19th Int. Symp. Space Terahertz Technol. (pp. 263–266).
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Karpov, A., Miller, D., Stern, J. A., Bumble, B., LeDuc, H. G., & Zmuidzinas, J. (2009). Broadband SIS mixer for 1 THz Band. In Proc. 20th Int. Symp. Space Terahertz Technol. (p. 35).
Abstract: We report the development of a low noise and broadband SIS mixer aimed for 1 THz channel of the Caltech Airborne Submillimeter Interstellar Medium Investigations Receiver (CASIMIR), designed for the Stratospheric Observatory for Far Infrared Astronomy, (SOFIA). The mixer uses an array of 0.24 µm² Nb/Al-AlN/NbTiN SIS junctions with critical current density of 30-50 KA/cm². The junctions are shaped in order to optimize the suppression of the Josephson DC currents. We are using a double slot planar antenna to couple the mixer chip with the telescope beam. The RF matching microcircuit is made using Nb and gold films. The mixer IF circuit is designed to cover 4 – 8 GHz band. A test receiver with the new mixer has a low noise operation in a 0.87 – 1.12 THz band. The minimum DSB receiver noise measured at 1 THz is 260 K (Y=1.64), apparently the lowest reported up to date. The receiver noise corrected for the loss in the LO injection beam splitter and in the cryostat window is 200 K. The combination of a broad operation band of about 250 GHz with a low receiver noise is making the new mixer a useful element for application at SOFIA. We will discuss the prospective of a further improvement of the sensitivity and extension of the upper frequency of operation of SIS mixer.
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Uzawa, Y., Kojima, T., Kroug, M., Takeda, M., Candotti, M., Fujii, Y., et al. (2009). Development of the 787-950 GHz ALMA band 10 cartridge. In Proc. 20th Int. Symp. Space Terahertz Technol. (p. 12).
Abstract: We are developing the Atacama Large Millimeter/Submillimeter Array (ALMA) Band 10 (787-950 GHz) receiver cartridge. The incoming beam from the 12-m antenna is reflected by a pair of two ellipsoidal mirrors placed in the cartridge, and then split into two orthogonal polarizations by a free-standing wire-grid. Each beam enters a corrugated feed horn attached to a double-side-band (DSB) mixer block. The mixer uses a full-height waveguide and an NbTiN- or NbN-based superconductor-insulator-superconductor (SIS) mixer chip. We are testing the following three types of mixer chips: 1) Nb SIS junctions + NbTiN/SiO2/Al tuning circuits on a quartz substrate, 2) Nb SIS junctions + NbN/SiO2/Al tuning circuits on an MgO substrate, and 3) NbN SIS junctions + NbN or NbTiN tuning circuits on an MgO substrate. The IF system uses a 4-12-GHz cooled low-noise InP-based MMIC amplifier developed by Caltech. So far, the type 1) has shown the best performance. At LO frequencies from 800 to 940 GHz, the mixer noise temperatures measured by using the standard Y-factor method were below 240 K at an operating physical temperature of 4 K. The lowest noise temperature, 169 K, was obtained at the center frequency of the band 10, as designed. These well-developed technologies will be implemented in the band 10 cartridge to achieve the ALMA specifications.
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Billade, B., Belitsky, V., Pavolotsky, A., Lapkin, I., & Kooi, J. (2009). ALMA band 5 (163-211 GHz) sideband separation mixer. In Proc. 20th Int. Symp. Space Terahertz Technol. (pp. 19–23).
Abstract: We present the design of ALMA Band 5 sideband separation SIS mixer and experimental results for the double side band mixer and first measurement results 2SB mixer. In this mixer, the LO injection circuitry is integrated on the mixer substrate using a directional coupler, combining microstrip lines with slot-line branches in the ground plane. The isolated port of the LO coupler is terminated by wideband floating elliptical termination. The mixer employs two SIS junctions with junction area of 3 µm² each, in the twin junction configuration, followed by a quarter wave transformer to match the RF probe. 2SB mixer uses two identical but mirrored chips, whereas each DSB mixer has the same end-piece configuration. The 2S mixer has modular design such that DSB mixers are measured independently and then integrated into 2SB simply by placing around the middle piece. Measurements of the DSB mixer show noise temperature of around 40K over the entire band. 2SB mixer is not fully characterized yet, however, preliminary measurement indicates SSB (un-corrected) noise temperature of 80K.
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Li, C. - T., Chen, T. - J., Ni, T. - L., Lu, W. - C., Chiu, C. - P., Chen, C. - W., et al. (2009). Development of SIS mixers for SMA 400-520 GHz band. In Proc. 20th Int. Symp. Space Terahertz Technol. (pp. 24–30).
Abstract: SIS junction mixers were developed for SMA 400-520 GHz band. The results show receiver noise temperature around 100 K across the band, with noise contribution from RF loss and IF estimated to be around 50 K and 20K, respectively. Two schemes were used to tune out junction's parasitic capacitance. When a parallel inductor is employed, the input impedance is close to Rn, which facilitates impedance matching between the junction and the waveguide probe. Waveguide probes were designed to achieve a low feed-point impedance to match to the junction resistance. Optimum embedding impedances for lower receiver noise temperature were investigated. Performances of two schemes and composition of receiver noise were also discussed.
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Jackson, B. D., Hesper, R., Adema, J., Barkhof, J., Baryshev, A. M., Zijlstra, T., et al. (2009). Series production of state-of-the-art 602-720 GHz SIS receivers for band 9 of ALMA. In Proc. 20th Int. Symp. Space Terahertz Technol. (pp. 7–11).
Abstract: The Atacama Large Millimeter/Sub-millimeter Array (ALMA) requires the development and production of 73 state-of-the-art receivers for the 602-720 GHz range – the ALMA Band 9 cartridges. Development and pre-production of the first 8 cartridges was completed between 2003 and 2008, resulting in a cartridge design that meets the project's challenging requirements. The cartridge design remains essentially unchanged for production, while the production and test processes developed during pre-production have been fine-tuned to address the biggest new challenge for this phase – ramping up production to a rate of 2 cartridges per month over 2009-2012.
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Kooi, J. W. (2008). Advanced receivers for submillimeter and far infrared astronomy. Doctoral thesis, , .
Keywords: HEB, SIS, TES, NEP, noise temperature, IF bandwidth, waveguide, impedance, conversion gain, FTS, integrated array, stability, Allan variance, multi-layer antireflection coating
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Ozhegov, R. V., Gorshkov, K. N., Vachtomin, Y. B., Smirnov, K. V., Finkel, M. I., Goltsman, G. N., et al. (2014). Terahertz imaging system based on superconducting heterodyne integrated receiver. In C. Corsi, & F. Sizov (Eds.), Proc. THz and Security Applications (pp. 113–125). Dordrecht: Springer Netherlands.
Abstract: The development of terahertz imaging instruments for security systems is on the cutting edge of terahertz technology. We are developing a THz imaging system based on a superconducting integrated receiver (SIR). An SIR is a new type of heterodyne receiver based on an SIS mixer integrated with a flux-flow oscillator (FFO) and a harmonic mixer which is used for phase-locking the FFO. Employing an SIR in an imaging system means building an entirely new instrument with many advantages compared to traditional systems.
In this project we propose a prototype THz imaging system using an 1 pixel SIR and 2D scanner. At a local oscillator frequency of 500 GHz the best noise equivalent temperature difference (NETD) of the SIR is 10 mK at an integration time of 1 s and a detection bandwidth of 4 GHz. The scanner consists of two rotating flat mirrors placed in front of the antenna consisting of a spherical primary reflector and an aspherical secondary reflector. The diameter of the primary reflector is 0.3 m. The operating frequency of the imaging system is 600 GHz, the frame rate is 0.1 FPS, the scanning area is 0.5 × 0.5 m2, the image resolution is 50 × 50 pixels, the distance from an object to the scanner was 3 m. We have obtained THz images with a spatial resolution of 8 mm and a NETD of less than 2 K.
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Samsonova, A., Zolotov, P., Baeva, E., Lomakin, A., Titova, N., Kardakova, A., et al. (2021). Signatures of surface magnetic disorder in thin niobium films. IEEE Trans. Appl. Supercond., , 1.
Abstract: We present our studies on the evolution of the normal and superconducting properties with thickness of thin Nb films with a low level of non-magnetic disorder (kFl 150 for the thickest film in the set). The analysis of the superconducting behavior points to the presence of magnetic moments, hidden in the native oxide on the surface of Nb films. Using the Abrikosov-Gorkov theory, we obtain the density of surface magnetic moments of 1013 cm-2, which is in agreement with the previously reported data for Nb films.
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Gayduchenko, I. A., Moskotin, M. V., Matyushkin, Y. E., Rybin, M. G., Obraztsova, E. D., Ryzhii, V. I., et al. (2018). The detection of sub-terahertz radiation using graphene-layer and graphene-nanoribbon FETs with asymmetric contacts. In Materials Today: Proc. (Vol. 5, pp. 27301–27306).
Abstract: We report on the detection of sub-terahertz radiation using single layer graphene and graphene-nanoribbon FETs with asymmetric contacts (one is the Schottky contact and one – the Ohmic contact). We found that cutting graphene into ribbons a hundred nanometers wide leads to a decrease of the response to sub-THz radiation. We show that suppression of the response in the graphene nanoribbons devices can be explained by unusual properties of the Schottky barrier on graphene-vanadium interface.
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Emelianov, A. V., Nekrasov, N. P., Moskotin, M. V., Fedorov, G. E., Otero, N., Romero, P. M., et al. (2021). Individual SWCNT transistor with photosensitive planar junction induced by two‐photon oxidation. Adv. Electron. Mater., 7(3), 2000872.
Abstract: The fabrication of planar junctions in carbon nanomaterials is a promising way to increase the optical sensitivity of optoelectronic nanometer-scale devices in photonic connections, sensors, and photovoltaics. Utilizing a unique lithography approach based on direct femtosecond laser processing, a fast and easy technique for modification of single-walled carbon nanotube (SWCNT) optoelectronic properties through localized two-photon oxidation is developed. It results in a novel approach of quasimetallic to semiconducting nanotube conversion so that metal/semiconductor planar junction is formed via local laser patterning. The fabricated planar junction in the field-effect transistors based on individual SWCNT drastically increases the photoresponse of such devices. The broadband photoresponsivity of the two-photon oxidized structures reaches the value of 2 × 107 A W−1 per single SWCNT at 1 V bias voltage. The SWCNT-based transistors with induced metal/semiconductor planar junction can be applied to detect extremely small light intensities with high spatial resolution in photovoltaics, integrated circuits, and telecommunication applications.
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Larrey, V., Villegier, J. - C., Salez, M., Miletto-Granozio, F., & Karpov, A. (1999). Processing and characterization of high Jc NbN superconducting tunnel junctions for THz analog circuits and RSFQ. IEEE Trans. Appl. Supercond., 9(2), 3216–3219.
Abstract: A generic NbN Superconducting Tunnel Junctions (STJ) technology has been developed using conventional substrates (Si and SOI-SIMOX) for making THz spectrometers including SIS receivers and RSFQ logic gates. NbN/MgO/NbN junctions with area of 1 /spl mu/m/sup 2/, Jc of 10 kA/cm/sup 2/ and low sub-gap leakage current (Vm>25 mV) are currently obtained from room temperature sputtered multilayers followed by a post-annealing at 250/spl deg/C. Using a thin MgO buffer layer deposited underneath the NbN electrodes, ensures lower NbN surface resistance values (Rs=7 /spl mu//spl Omega/) at 10 GHz and 4 K. Epitaxial NbN [100] films on MgO [100] with high gap frequency (1.4 THz) have also been achieved under the same deposition conditions at room temperature. The NbN SIS has shown good I-V photon induced steps when LO pumped at 300 GHz. We have developed an 8 levels Al/NbN multilayer process for making 1.5 THz SIS mixers (including Al antennas) on Si membranes patterned in SOI-SIMOX. Using the planarization techniques developed at the Si-MOS CEA-LETI Facility, we have also demonstrated on the possibility of extending our NbN technology to high level RSFQ circuit integration with 0.5 /spl mu/m/sup 2/ junction area, made on large area substrates (up to 8 inches).
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Gayduchenko, I., Xu, S. G., Alymov, G., Moskotin, M., Tretyakov, I., Taniguchi, T., et al. (2021). Tunnel field-effect transistors for sensitive terahertz detection. Nat. Commun., 12(1), 543.
Abstract: The rectification of electromagnetic waves to direct currents is a crucial process for energy harvesting, beyond-5G wireless communications, ultra-fast science, and observational astronomy. As the radiation frequency is raised to the sub-terahertz (THz) domain, ac-to-dc conversion by conventional electronics becomes challenging and requires alternative rectification protocols. Here, we address this challenge by tunnel field-effect transistors made of bilayer graphene (BLG). Taking advantage of BLG's electrically tunable band structure, we create a lateral tunnel junction and couple it to an antenna exposed to THz radiation. The incoming radiation is then down-converted by the tunnel junction nonlinearity, resulting in high responsivity (>4 kV/W) and low-noise (0.2 pW/[Formula: see text]) detection. We demonstrate how switching from intraband Ohmic to interband tunneling regime can raise detectors' responsivity by few orders of magnitude, in agreement with the developed theory. Our work demonstrates a potential application of tunnel transistors for THz detection and reveals BLG as a promising platform therefor.
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