Title Enabling high sensitivity patch-antenna-coupled TeraFETs for the above 1-THz frequency band using superstrate Lenses
Authors Holstein, Jakob ; But, Dmytro B ; Krysl, Anastasiya ; Lisauskas, Alvydas ; Roskos, Hartmut G
DOI 10.1007/s10762-026-01147-y
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Is Part of Journal of infrared, millimeter, and terahertz waves.. Springer. 2026, vol. 47, iss. 6, art. no. 41, p. 1-21.. ISSN 1866-6892. eISSN 1866-6906
Keywords [eng] 65-nm CMOS ; field-effect transistor ; radiation ; THz detection ; superstrate lens ; passive sensing
Abstract [eng] Antenna-coupled field-effect transistors (TeraFETs) have emerged as a class of room-temperature THz detectors capable of competing with Schottky-barrier diodes in sensitivity and response speed. A key advantage of FET-based detectors is their compatibility with mature semiconductor foundry processes, enabling scalable, high-yield fabrication (e.g., 65-nm Si CMOS). Quasi-optical detectors employing planar, ground-plane-free antennas achieve maximum responsivity under substrate lens illumination. However, resonant patch-antenna-coupled FETs cannot employ this configuration due to the presence of a buried metallic ground plane. In [1], we introduced superstrate-coupling strategies for patch antenna-coupled FET resonant at 580 GHz. Here, we investigate eleven front-side-illuminated, superstrate lens-coupled detectors with resonance frequencies between 0.5 and 2.5 THz. A key result is that the minimum optical noise-equivalent power (NEP)—defined relative to the total incident beam power—around the resonance frequencies increases significantly less with frequency than in waveguide-coupled Schottky-barrier diode technology. While the investigated detectors exhibit slightly higher NEP below 1 THz, they outperform commercial Schottky-barrier diodes above 1.5 THz. Compared with TeraFETs employing broadband antennas, patch-coupled FETs provide substantially improved performance at their resonance frequencies. Minimum optical NEP values between $$16\,\text {pW}/\sqrt{\text {Hz}}$$ 16 pW / Hz at 0.52 THz and $$43\,\text {pW}/\sqrt{\text {Hz}}$$ 43 pW / Hz at 2.45 THz were achieved and confirmed by broadband thermal radiation measurements. The results are further compared with substrate-lens-coupled detectors employing log-spiral and other broadband antennas reported in the literature.
Published Springer
Type Journal article
Language English
Publication date 2026
CC license CC license description