Abstract 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\, pW/ Hz 16 pW / Hz at 0. 52 THz and 43\, pW/ 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.
Holstein et al. (2026) studied this question.