Ekström, H., Karasik, B., Kollberg, E., & Yngvesson, K. S. (1994). Investigation of a superconducting hot electron mixer. In Proc. 5th Int. Symp. Space Terahertz Technol. (pp. 169–188).
Abstract: Mixing at 20 GHz in niobium superconducting thin film strips in the resistive state is studied. Experiments give evidence that electron-heating is the main cause of the non linear phenomena. The requirements on the mode of operation and on the film parameters for small conversion loss and the possibility of conversion gain are discussed. Measurements indicate a minimum intrinsic conversion loss around 1 dB with a sharp drop for the lowest voltage bias-points, and a DSB mixer noise temperature between 100 and 450 K at 20 GHz. The device output noise temperature at the mixer operating point can be as low as 30-50 K. A simple theory is presented, which is based on the assumption that the small signal resistance is linearly dependent on power. This type of mixer is considered very promising for use in low-noise heterodyne receivers at THz frequencies.
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Gol'tsman, G., Jacobsson, S., Ekstrom, H., Karasik, B., Kollberg, E., & Gershenzon, E. (1994). Slot-line tapered antenna with NbN hot electron mixer for 300-360 GHz operation. In Proc. 5th Int. Symp. Space Terahertz Technol. (pp. 209–213a).
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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0kunev, 0., Dzardanov, A., Ekstrom, H., Jacobsson, S., Kollberg, E., Gol'tsman, G., et al. (1994). NbN hot electron waveguide mixer for 100 GHz operation. In Proc. 5th Int. Symp. Space Terahertz Technol. (pp. 214–224).
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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Elantev, A. I., & Karasik, B. S. (1994). Noise temperature of a superconducting hot-electron mixer. In Proc. 5th Int. Symp. Space Terahertz Technol. (225).
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Ekstrom, H., Karasik, B., Weikle, R., Yngvesson, K. S., Gol’tsman, G., Kollberg, E., et al. (1993). Mixers using superconducting Nb films in the resistive state. In 23rd European Microwave Conf. (pp. 787–789).
Abstract: The mixing of 20 GHz radiation in a Nb superconducting film in the resistive state was studied. The experiment gave evidence of electron-heating to be the origin of the non-linear phenomenon. The requirements on the operation mode and on the film parameters in order to obtain small conversion losses or even gain are determined. Our measurements indicate a conversion loss of about 6-8 dB. The hot-electron bolometer is considered to be very promising for use in heterodyne receivers in a wide frequency range from microwaves to terahertz frequencies.
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Gershenzon, E. M., & Gol'tsman, G. N. (1993). Hot electron superconductive mixers. In Proc. 4th Int. Symp. Space Terahertz Technol. (pp. 618–622).
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Gol'tsman, G. N., Elant'iev, A. I., Karasik, B. S., & Gershenzon, E. M. (1993). Antenna – coupled superconducting electron-heating bolometer. In Proc. 4th Int. Symp. Space Terahertz Technol. (pp. 623–628).
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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Kollberg, E. L., Gershenzon, E., Goltsman, G., & Yngvesson, K. S. (1992). Hot electron mixers, the potential competition. In Proc. ESA Symp. on Photon Detectors for Space Instrumentation (pp. 201–206).
Abstract: There is an urgent need in radio astronomy for low noise heterodyne receivers for frequencies above about 500 GHz. It is not certain that mixers based on superconducting quasiparticle tunnelling (SIS mixers) may turn out to be the answer to this need. In order to try to find an alternative way for realizing low noise heterodyne receivers for submillimeter waves, so called hot electron bolometric effects for mixing are now being investigated. Two basically different approaches are tried, one based on semiconductors and one on superconductors. Both methods are briefly discussed in this overview paper.
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Gershenzon, E. M., Gol’tsman, G. N., Sergeev, A., & Semenov, A. D. (1990). Picosecond response of YBaCuO films to electromagnetic radiation. In W. Gorzkowski, M. Gutowski, A. Reich, & H. Szymczak (Eds.), Proc. European Conf. High-Tc Thin Films and Single Crystals (pp. 457–462).
Abstract: Radiation-induced change of the resistance was studied in the resistive state of YBaCuO films. Electron-phonon relaxation time T h was determmed from direct ep measurements and analysis of quasistationary electron heating. Temperature dependence of That TS 40 K was found to – ep be T h.. T'. The resul ts show that ep detectors with the response time of few picosecond at nitrogen temperature can be realized.
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Gershenzon, E. M., Goltsman, G. N., & Orlov, L. (1976). Investigation of population and ionization of donor excited states in Ge. In Physics of Semiconductors (pp. 631–634). North-Holland Publishing Co.
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