Low noise submillimeter SIS receiver with niobium nitride quasiparticle tunnel junctions |
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Authors: | A Karpov B Plathner J Blondel M Schicke K H Gundlach M Aoyagi and S Takada |
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Institution: | (1) Institut de Radioastronomie Millimétrique, Domaine Universitaire de Grenoble, 300, rue de la Piscine, F-38406 St. Martin d'Hères, France;(2) Electrotech. Lab. 1-1-4 Umezono Tsukuba - shi, 305 Ibaraki, Japan |
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Abstract: | We have developed and tested a submillimeter waveguide SIS mixer with NbN-MgO-NbN quasiparticle tunnel junctions. The two junction array is integrated in a full NbN printed circuit. The NbN film critical temperature is 15 K and the junction gap voltage is 5 mV. The size of the junctions is 1.4 × 1.4 µm and Josephson critical current density is about 1.5 KA/cm2 resulting in junction RN C product about 40. The inductive tuning circuit in NbN is integrated with each junction in two junction array. A single non contacting backshort was tuned at each frequency in the mixer block.At 306 GHz the minimum DSB receiver noise temperature is as low as 230 K. The sources of the receiver noise and of the limits of the NbN SIS submillimeter mixer improvement are discussed. |
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Keywords: | superconductors NbN SIS junction SIS mixer SIS receiver low noise submillimeter waves radioastronomy |
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