The phenomena and recent progress in the evolution of the basic classes of the THz detectors that exist today are considered. Issues associated with the development and exploitation of THz radiation detectors in human activity applications are briefly addressed. The operation conditions of the THz detectors and their upper limit performance are discussed. Because of lack of space not all the important references will be mentioned. Where reasonable, mainly publications after 2011 are addressed.

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.

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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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A model of semiconductor hot electron bolometer (SHEB), in which electromagnetic radiation heats only electrons in narrow-gap semiconductor without its lattice slow-response heating, is considered. Free carrier heating changes the generation-recombination processes that are the reason of semiconductor resistance rise. It is estimated, that Hg0.8Cd0.2Te detector noise equivalent power (NEP) for mm and sub-mm radiation wavelength range can reach NEP ∼10−11 W at Δf = 1 Hz signal gain frequency bandwidth. Measurements performed at electromagnetic wave frequencies v = 36, 39, 55, 75 GHz, and at 0.89 and 1.58 THz too, with non-optimized Hg0.8Cd0.2Te antenna-coupled bolometer prototype confirmed the basic concept of SHEB. The experimental sensitivity Sv ∼2 V/W at T = 300 K and the calculated both Johnson-Nyquist and generation-recombination noise values gave estimation of SHEB NEP ∼3.5 × 10−10 W at the band-width Δf = 1 Hz and v = 36 GHz.

Effects of the enhancement of photoconductivity in 2D photonic macroporous silicon structures were investigated. Dependence of photoconductivity on the angle of incidence of the electromagnetic radiation is observed with maxima at normal incidence of electromagnetic radiation, in the region of the angle of full internal reflection respective to macropore walls and at a grazing angle of incidence respective to the surface of structure. The absolute maximum of photoconductivity is measured at distance between macropores, corresponding to two lengths of the electron free run, i.e. by the maximal transfer of the amplified electric components from a macropore surface in a silicon matrix. Angular dependences of photoconductivity, as well as enhancement of the photoconductivity in comparison with monocrystal silicon, primary absorption p-component of electromagnetic radiation testified to formation of surface electromagnetic waves in illuminated macrporous silicon structures. Its effects result in amplification of a local electric field on a surface of macroporous silicon structure and a macropore surface. The measured value of the built-in electric field on a macropore surface achieves 1 06 V/cm, the signal of photoconductivity amplifies 1 02 times, and Raman scattering -up to one order of value.

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