Bandwidth of Nb/AlN/Nb SIS Mixers Suitable for Frequencies around 700 GHz

Abstract — We have developed a new fabrication process for AlN barriers with excellent reproducibility and control compared to previous work, enabling the use of these barriers in SIS mixers. We report results with niobium-aluminum nitride-niobium superconductor-isolator-superconductor (SIS) mixers for 700 GHz, demonstrating a wide bandwidth behavior with Fourier Transform Spectrometer (FTS) measurements. These measurements have been performed in air and reveal that the bandwidth is no longer limited by the tuning circuit but by the atmospheric absorption of radiation. We also present noise temperature measurements of AlN SIS mixers that complement the FTS results. I