This article describes a novel approach to measure responsivity of a FET-based sub-THz detector using on-wafer probes to directly feed a bare antenna-less detecting device. Thus, the approach eliminates the need to know beforehand the detector’s effective aperture, which can be a source of large variation between responsivity measurements of various FET-based detectors often cited in the literature. It seems that the presented method can be useful at making direct comparisons between responsivity of various devices (e.g., MOSFETs, HEMTs etc.). As a demonstration, the sub-THz responsivity of a pHEMT device fabricated using a commercial GaAs process has been measured in a WR-3 frequency band. Additionally, the results have been compared against data obtained using an alternative approach. The verification method consisted in integrating exactly the same device with a broad-band antenna and a carefully selected high-resistivity silicon lens and comparing its performance with that of a commercial calibrated detector based on Schottky diodes.

Recent advances in THz detection with the use of CMOS technology have shown that this option has the potential to be a leading method of producing low-cost THz sensors with integrated readout systems. This review paper, based on authors’ years of experience, presents strengths and weaknesses of this solution. The article gives examples of some hints, regarding radiation coupling and readout systems. It shows that silicon CMOS technology is well adapted to the production of inexpensive imaging systems for sub-THz frequencies. As an example paper presents the demonstrator of a multipixel Si-CMOS THz spectroscopic system allowing for chemical identification of lactose. The THz detectors embedded in this system were manufactured using the CMOS process.