ABSTRACT
This chapter presents an overview of the Nb-based tunnel junction's technology at Kotelnikov IREE in Moscow. By improving on the fully Nb-based SIR, the chapter develops and studies Nb-AlN-NbN circuits that exhibit an extended operation frequency range. Continuous frequency tuning for the phase-locked superconducting local oscillators (LO) has been experimentally demonstrated in the range of 350-750 GHz. As a result of Nb-AlOx-Nb technology optimization and extensive analysis of the SIS receiver designs, a number of low-noise receivers have been designed and tested. The Josephson flux flow oscillators based on Nb-AlOx-Nb and Nb-AlN-NbN junctions have proven to be the most developed superconducting local oscillator for integration with an SIS mixer in a single-chip submicrometer-wave superconducting integrated receiver. The implementation of an AlN tunnel barrier in combination with a NbN top superconducting electrode is expected to give a significant improvement in SIS THz mixer performance. High-quality Nb-AlN-NbN tunnel junctions were used for development of the superconducting LO and fully integrated superconducting receivers.
