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Field-effect transistor based detectors for power monitoring of THz quantum cascade lasers

: Zdanevicius, Justinas; Cibiraite, Dovile; Ikamas, Kestutis; Bauer, Maris; Matukas, Jonas; Lisauskas, Alvydas; Richter, Heiko; Hagelschuer, Till; Krozer, Viktor; Hübers, Heinz-Wilhelm; Roskos, Hartmut G.


IEEE Transactions on Terahertz Science and Technology 8 (2018), Nr.6, S.613-621
ISSN: 2156-342X
Fraunhofer ITWM ()
terahertz detector; plasmonic detection; SOFIA; GREAT; THz QCL

We report on circuit simulation, modeling, and characterization of field-effect transistor based terahertz (THz) detectors (TeraFETs) with integrated patch antennas for discrete frequencies from 1.3 to 5.7 THz. The devices have been fabricated using a standard 90-nm CMOS technology. Here, we focus in particular on a device showing the highest sensitivity to 4.75-THz radiation and its prospect to be employed for power monitoring of a THz quantum cascade laser used in a heterodyne spectrometer GREAT (German REceiver for Astronomy at Terahertz frequencies). We show that a distributed transmission line based detector model can predict the detector's performance better than a device model provided by the manufacturer. The integrated patch antenna of the TeraFET designed for 4.75 THz has an area of 13×13 μ m 2 and a distance of 2.2 μ m to the ground plane. The modeled radiation efficiency at the target frequency is 76% with a maximum directivity of 5.5, resulting in an effective area of 1750 μ m 2 . The detector exhibits an area-normalized minimal noise-equivalent power of 404 pW/√Hz and a maximum responsivity of 75 V/W. These values represent the state of the art for electronic detectors operating at room-temperature and in this frequency range.