The model of long channel unbiased field effect transistor (FET) as mm-wave/THz detector is developed with account of some parasitic effects. The model offered is compared with the other known FET detector models and experimental data. The obtained responsivity (R) and noise equivalent power (NEP) estimations were compared with those for Schottky barrier diode (SBD) detectors. Within the framework of the model, R and NEP values for Si FETs can be determined in all inversion regions. Limits for performance of these detectors have been estimated. It has been shown that with advanced FET technology, the performance of FET mm-wave/THz detectors can be made similar to that of SBD ones or in high frequency range can surpass it. Influence of parasitic effects and detector-antenna matching on detector parameters is discussed. It has been ascertained that FETs can be preferable in some applications due to smaller parasitic effects.

Some problems and challenges for applications of uncooled or slightly cooled detectors (not deeper than to 77 K) for sub-THz and THz (terahertz) arrays are briefly discussed. The possibilities to involve detectors based on plasmon resonance FETs (field effect transistors) and those based on warm electron effect narrow-gap semiconductor bolometers are speculated, as they seem to be promising for using in large format broadband arrays of low-cost systems, though they are still in the stage of research and optimization.

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We present an overview of our technological achievements in the implementation of detector structures based on mercury cadmium telluride (MCT) heterostructures and nanostructures for IR and THz spectral ranges. We use a special MBE design set for the epitaxial layer growth on (013) GaAs substrates with ZnTe and CdTe buffer layers up to 3" in diameter with the precise ellipsometric monitoring in situ. The growth of MCT alloy heterostructures with the optimal composition distribution throughout the thickness allows for the realization of different types of many-layered heterostructures and quantum wells to prepare the material for fabricating single-or dual-band IR and THz detectors.We also present the two-color broad-band bolometric detectors based on the epitaxial MCT layers that are sensitive in 150-300-GHz subterahertz and infrared ranges from 3 to 10 m, which operate at the ambient or liquid nitrogen temperatures as photoconductors, as well as the detectors based on planar HgTe quantum wells. The design and dimensions of THz detector antennas are optimized for reasonable detector sensitivity values. A special diffraction limited optical system for the detector testing was designed and manufactured. We represent here the THz images of objects hidden behind a plasterboard or foam plastic packaging, obtained at the radiation frequencies of 70, 140, and 275 GHz, respectively.