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An, Z., Chen, J. - C., Ueda, T., Komiyama, S., & Hirakawa, K. (2005). Infrared phototransistor using capacitively coupled two-dimensional electron gas layers. Appl. Phys. Lett., 86, 172106-3.
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Koshelets, V. P., Dmitriev, P. N., Ermakov, A. B., Filippenko, L. V., Koryukin, O. V., Torgashin, M. Y., et al. (2005). Integrated superconducting spectrometer for atmosphere monitoring. Radiophys. Quant. Electron., 48(10-11), 844–850.
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Hübers, H. W., Pavlov, S. G., Semenov, A. D., Tredicucci, A., Köhler, R., Mahler, L., et al. (2005). Investigation of a 2.5 THz quantum cascade laser as local oscillator. In Proc. 16th Int. Symp. Space Terahertz Technol. (18). Göteborg, Sweden.
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Vaks, V. L., Kurin, V. V., Pankratov, A. L., & Koshelets, V. P. (2005). Investigation of spectral properties of phase-focked flux flow oscillator. In ISEC (PD-04). Netherlands.
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Hajenius, M., Barends, R., Gao, J. R., Klapwijk, T. M., Baselmans, J. J. A., Baryshev, A., et al. (2005). Local resistivity and the current-voltage characteristics of hot electron bolometer mixers. IEEE Trans. Appl. Supercond., 15(2), 495–498.
Abstract: Hot-electron bolometer devices, used successfully in low noise heterodyne mixing at frequencies up to 2.5 THz, have been analyzed. A distributed temperature numerical model of the NbN bridge, based on a local electron and a phonon temperature, is used to model pumped IV curves and understand the physical conditions during the mixing process. We argue that the mixing is predominantly due to the strongly temperature dependent local resistivity of the NbN. Experimentally we identify the origins of different transition temperatures in a real HEB device, suggesting the importance of the intrinsic resistive transition of the superconducting bridge in the modeling.
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Karpov, A., Miller, D., Stern, J. A., Bumble, B., LeDuc, H. G., & Zmuidzinas, J. (2005). Low noise NbTiN 1.25 THz SIS mixer for Herschel Space Observatory. In Proc. 16th Int. Symp. Space Terahertz Technol. (450). Göteborg, Sweden.
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Goltsman, G. N., Vachtomin, Y. B., Antipov, S. V., Finkel, M. I., Maslennikov, S. N., Polyakov, S. L., et al. (2005). Low-noise NbN phonon-cooled hot-electron bolometer mixers for terahertz heterodyne receivers. In Proc. 9-th WMSCI (Vol. 9, pp. 154–159). International Institute of Informatics and Systemics.
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Palermo, C., Varani, L., Vaissière, J. - C., Millithaler, J. - F., Starikov, E., Shiktorov, P., et al. (2005). Monte Carlo calculation of diffusion coefficient, noise spectral density and noise temperature in HgCdTe. In Proc. AIP Conf. (Vol. 780, pp. 151–154).
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Baselmans, J. J. A., Hajenius, M., Gao, J. R., Baryshev, A., Kooi, J., Klapwijk, T. M., et al. (2005). NbN hot electron bolometer mixers: sensitivity, LO power, direct detection and stability. IEEE Trans. Appl. Supercond., 15(2), 484–489.
Abstract: We demonstrate that the performance of NbN lattice cooled hot electron bolometer mixers depends strongly on the interface quality between the bolometer and the contact structure. Both the receiver noise temperature and the gain bandwidth can be improved by a factor of 2 by cleaning the interface and adding an additional superconducting interlayer to the contact pad. Using this we obtain a double sideband receiver noise temperature of 950 K at 2.5 THz and 4.3 K, using a 0.4/spl times/4 /spl mu/m HEB mixer with a spiral antenna. At the same bias point, we obtain an IF gain bandwidth of 6 GHz. To comply with current demands on THz mixers for use in space based receivers we reduce the device size to 0.15/spl times/1 /spl mu/m and use a twin slot antenna. We report measurements of the noise temperature, LO power requirement, stability and the direct detection effect, using a mixer with a 1.6 THz twin slot antenna and a 1.462 THz solid state LO source with calibrated output power.
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Gol'tsman, G. N., Vachtomin, Y. B., Antipov, S. V., Finkel, M. I., Maslennikov, S. N., Smirnov, K. V., et al. (2005). NbN phonon-cooled hot-electron bolometer mixer for terahertz heterodyne receivers. In Proc. SPIE (Vol. 5727, pp. 95–106).
Abstract: We present the results of our studies of NbN phonon-cooled HEB mixers at terahertz frequencies. The mixers were fabricated from NbN film deposited on a high-resistivity Si substrate with an MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 x 0.2 μm2 active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. The largest gain bandwidth of 5.2 GHz was achieved for a mixer based on 2 nm thick NbN film deposited on MgO layer over Si substrate. The gain bandwidth of the mixer based on 3.5 nm NbN film deposited on Si with MgO is 4.2 GHz and the noise bandwidth for the same device amounts to 5 GHz. We also present the results of our research into decrease of the direct detection contribution to the measured Y-factor and a possible error of noise temperature calculation. The use of a square nickel cell mesh as an IR-filter enabled us to avoid the effect of direct detection and measure apparent value of the noise temperature which was 16% less than that obtained using conventional black polyethylene IR-filter.
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