A High-Sensitivity AlGaN/GaN HEMT Terahertz Detector With Integrated Broadband Bow-Tie Antenna
IEEE Trans. Terahertz Sci. Technol., vol. 9, no. 4, pp. 430-444 (2019).
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Many emerging applications in the terahertz (THz)frequency range demand highly sensitive, broadband detectors for room-temperature operation. Field-effect transistors with integrated antennas for THz detection (TeraFETs) have proven to meet these requirements, at the same time offering great potential for scalability, high-speed operation, and functional integrability. In this contribution, we report on an optimized field-effect transistor with integrated broadband bow-tie antenna for THz detection (bow-tie TeraFET) and compare the detector’s performance to other state-of-the-art broadband THz detector technologies. Implemented in a recently developed AlGaN/GaN MMIC process, the presented TeraFET shows a more than twice performance improvement compared to previously fabricated AlGaN/GaN-HEMT-based TeraFETs. The detector design is the result of detailed modeling of the plasma-wave-based detection principle embedded in a full-device detector model to account for power coupling of the THz radiation to the intrinsic gated FET channel. The model considers parasitic circuit elements as well as the high-frequency impedance of the integrated broadband antenna, and also includes optical losses from a silicon substrate lens. Calibrated characterization measurements have been performed at room temperature between 490 and 645 GHz, where we find values of the optical (total beam power referenced) noise-equivalent power of 25 and 31 pW/√Hz at 504 and 600 GHz, respectively, in good agreement with simulation results. We then show the broadband detection capability of our AlGaN/GaN detectors in the range from 0.2 to 1.2 THz and compare the TeraFETs’ signal-to-noise ratio to that of a Golay cell and a photomixer. Finally, we demonstrate animaging application in reflection geometry at 504 GHz and determine a dynamic range of >40 dB.
1 was with Physikalisches Institut, Johann Wolfgang Goethe-Universität, D-60438 Frankfurt am Main, Germany
2 now with the Center for Materials Characterization and Testing, Fraunhofer ITWM, D-67663 Kaiserslautern, Germany
3 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany
4 Institute of Applied Electrodynamics and Telecommunications, Vilnius University, LT-10257 Vilnius, Lithuania
5 General Jonas Zemaitis Military Academy of Lithuania, LT-10322 Vilnius, Lithuania
6 Center for Terahertz Researchand Applications, Institute of High Pressure Physics PAS, PL-01-142 Warsaw, Poland
Broadband antenna, field-effect transistors, GaNHEMT, plasmonic mixing, terahertz (THz) detectors.