GaAs field effect-transistors are used for single-pixel imaging using frequencies above 1 THz at 300 K. Images obtained in transmission mode at 1.63 THz are recorded with spatial resolution of 300 mu m. We demonstrate that, with applied drain to source current, the imaging at up to 2.5 THz is possible.

Resonant frequencies of the two-dimensional plasma in FETs reach the THz range for nanometer transistor channels. Non-linear properties of the electron plasma are responsible for detection of THz radiation with FETs. Resonant excitation of plasma waves with sub-THz and THz radiation was demonstrated for short gate transistors at cryogenic temperatures. At room temperature, plasma oscillations are usually over-damped, but the FETs can still operate as efficient broadband THz detectors. The paper presents the main theoretical and experimental results on detection with FETs stressing their possible THz imaging applications. We discuss advantages and disadvantages of application of III-V GaAs and GaN HEMTs and silicon MOSFETs.

Room temperature photovoltaic non-resonant detection by large area double-grating-gate InGaP/InGaAs/GaAs heterostructures was investigated in sub-THz range (0.24 THz). Semi-quantitative estimation of the characteristic detection length combined with self-consistent calculations of the electric fields excited in the structure by incoming terahertz radiation allowed us to interpret quantitatively the results and conclude that this detection takes place mainly in the regions of strong oscillating electric field excited in depleted portions of the channel.

GaAs nanometric field effect-transistors are used for room temperature single-pixel imaging using radiation frequencies above 1 THz. Images obtained in transmission mode at 1.63 THz are recorded using transistors operating in a photovoltaic mode with spatial resolution of 300 mu m and voltage sensitivity of about 8 mV/W. A reduction in response with increasing frequency was observed and mitigated by the application of a source-drain current, leading to the demonstration of imaging at up to 2.54 THz.

Because of their competitive Noise Equivalent Power (NEP) at room temperature and their fast modulation frequency, Field Effect Transistors (FETs) are one of the most promising devices for room temperature multipixel THz detection and imaging. We report here on an experimental study of the sub-THz detection as a function of the gate length in Silicon FETs and discuss the physical basis of their optimisation.

We observed a photovoltaic non-resonant terahertz photoresponse in a InGaAs/GaAs heterostructure with a large area double-grating-gate at room temperature. Semi-quantitative estimation of the characteristic detection length combined with self-consistent calculations of the electric fields exited in the structure by incoming terahertz radiation allowed us to interpret this detection as coming from the depleted regions of the channel.

Two experiments demonstrate that high electron mobility transistors (HEMTs) are well suited for terahertz (THz) imaging. We have shown that HEMTs can be effectively used as plasma wave detectors in a THz imaging system at frequencies higher than 1 THz at room temperature and this device are sensitive to the polarization direction of THz radiation.