Title :
Bandwidth Limitations of Nb/AlN/Nb SIS Mixers Around 700 GHz
Author :
Lodewijk, Chris F J ; Zijlstra, T. ; Zhu, Shaojiang ; Mena, F. Patricio ; Baryshev, Andrey M. ; Klapwijk, T.M.
Author_Institution :
Kavli Inst. of Nanosci., Delft Univ. of Technol., Delft, Netherlands
fDate :
6/1/2009 12:00:00 AM
Abstract :
We study, using niobium-technology, the bandwidth of SIS mixers operating at frequencies close to the energy-gap frequency. Microstriplines of niobium-silicon dioxide-niobium have different properties for the top and bottom superconductor, which we find to depend on the used fabrication process. Replacing the AlOx tunnel barrier by AlN, the bandwidth increases by 53%. The measurements, using a Fourier Transform Spectrometer (FTS) and performed in ambient air, demonstrate that the bandwidth is no longer limited by the tuning circuit but by the atmospheric absorption of radiation. Excellent noise temperatures are found over a full band of 600 to 720 GHz.
Keywords :
Fourier transform spectrometers; aluminium compounds; circuit tuning; microstrip lines; mixers (circuits); niobium; superconducting energy gap; AlOx tunnel barrier; Fourier transform spectrometer; SIS mixers; atmospheric absorption; bandwidth limitations; energy-gap frequency; fabrication process; microstriplines; niobium-technology; noise temperatures; superconductor; tuning circuit;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2009.2018231
