Program and Abstract Book - SRON

19 th International Symposium on Space Terahertz Technology
2-2
NbZr films for THz phonon-cooled HEB mixers.
Andrey Smirnov, Pavel Larionov, Matvey Finkel, Sergey Maslennikov, Boris Voronov and
Gregory Goltsman
Moscow State Pedagogical University, Moscow 119992, Russia
Heterodyne receivers demonstrate great potential for the detection of
electromagnetic radiation in the terahertz frequency range. At present, these
detectors are used to facilitate the realization of such projects like
HERSCHEL, SOFIA, TELIS , MILLIMETRON, etc.
Now NbN HEB mixers are the most sensitive detectors for heterodyne
spectrometers between 1 to 6 THz. Unique characteristics make NbN HEBs
highly attractive for both ground- and space-based telescopes.
Important mixer parameter is the IF bandwidth. Obviously a larger IF
bandwidth allows for simultaneous observation of several lines, or
instantaneous measurement of a single broad line. State of the art for IF
bandwidth of NbN HEB is about 5 GHz, however it is desirable to get wider
bandwidth achievable. Among different methods of IF bandwidths extension
one of the most prospective approaches is the looking for alternative
superconducting films, which will allow improving this key parameter. This
work is devoted to the investigation of the applicability of NbZr film as a new
material for ultrawide bandwidth HEB mixer. In this work we tested first NbZr
bridges and observed IF bandwidth which is comparable with that of NbN
structure of the same dimensions and at the same RF frequency. The further
work will be the research of electron-phonon time and escape time of
nonequilibrium phonons for the structure with smaller thickness that will
clarity the next perspectives of this material for HEB mixer technologies. This
result will also be reported at the Symposium.
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