FBH’s high-performance FET-based THz detectors reach user level
The terahertz (THz) frequency range is attractive for various applications in biology, medicine and industry because many materials have a characteristic spectral fingerprint or are transparent at these frequencies. A prerequisite for mass market applications at THz frequencies is the availability of high-performance THz detectors based on field effect transistors (TeraFETs). TeraFETs are able to work at room temperature with excellent sensitivity, even beyond classical diode-based performance. Moreover, easy and inexpensive mass production is possible in a standard MMIC process. In addition, planar chip antenna technology alleviates classical high-cost THz waveguide technology.
Based on its GaN HEMT MMIC process, the FBH develops state-of-the-art TeraFETs. To achieve this, different types of epitaxial structures, transistor layouts and antenna structures have been investigated. This extensive examination led to a patent-protected design principle (1), overcoming the classical separation between HEMT device and antenna. Based on this detector technology, a ready-to-use THz detector has been developed. This benchtop device combines the excellent TeraFET’s performance with an easy-to-use interface. It also offers the unique possibility of electronic chopping. Fig. 1 shows the THz detector in housing with lens-based THz coupling. Fig. 2 illustrates the broadband responsivity of the THz detector with a log-spiral detector structure, well beyond what is possible with waveguide detectors.
In many industrial applications, fast line scans or focal plane cameras are mandatory. Therefore, FBH is working on arrays of THz detectors, in order to maintain the excellent single detector performance in case of THz cameras. Fig. 3 demonstrates first 12 x 12 pixel focal plane arrays of THz detectors using bow-tie antennas. The chip area is 5 mm x 5 mm with a pixel pitch of 380 µm. These arrays can be stitched for larger THz camera arrays.
 M. Bauer, A. Rämer, S.i A. Chevtchenko, K. Osipov, D. Cibiraite, S. Pralgauskaite, K. Ikamas , A. Lisauskas, W. Heinrich, V. Krozer ,H. G. Roskos, "A High-Sensitivity AlGaN/GaN HEMT Terahertz Detector With Integrated Broadband Bow-Tie Antenna", in IEEE Transactions on Terahertz Science and Technology, vol. 9, no. 4, pp. 430-444, doi: 10.1109/TTHZ.2019.2917782, July (2019).
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Strahlungsdetektor und Verfahren zu dessen Herstellung - WO 2018/153557 - DE 10 2017 103 687 B3