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In this paper, an overview of main results concerning THz detection by nanometer field effect transistors (FETs) and heterojunction based transistors (HBTs) is presented. Different GaInAs/InP and GaN/AlGaN nanometer field effect transistors based detectors are presented. We present also first Silicon C-MOS transistors based integrated circuits for wireless communication in sub-THz range. Special attention...
We present the low frequency noise and the photoresponse in InP double heterojunction bipolar transistor (DHBT) THz detectors. A current responsivity of 0.23 A/W and a noise equivalent power of 4·10−10 W/Hz1/2 have been measured at 1 kHz modulation frequency. The collector bias can substantially reduce the noise equivalent power.
We report on THz emission from HgCdTe bulk films. Our experiments clearly show magnetically tunable THz emission that can be attributed to electron radiative recombination between the Landau levels (cyclotron emission). Energy band structure theoretical calculations using Kane Hamiltonian are performed. They allow identification of observed resonances as related to transitions between two lowest conduction...
Recent developments of THz detector arrays based on plasma wave field effect transistors are presented. By simultaneous development of the transistor arrays with their read-out circuits and diffractive 3D printed optics we demonstrate systems for imaging in 300 GHz atmospheric window with cameras or fast linear scanner. The first high speed THz postal scanner developed for real time fast A4 envelopes...
An overview of main results concerning THz detection related to plasma nonlinearities in nanometer field effect transistors is presented. In particular nonlinearity and dynamic range of these detectors are discussed. As a conclusion, we will show one of the first real world application of the FET THz detectors: a demonstrator of the imager developed for fast postal security.
Experimental and theoretical investigations of the influence of substrate thickness on the performance of Si field effect transistor terahertz detectors are presented‥ We show that in the case of planar metal antennas a significant portion of incoming radiation, instead of being coupled to the transistors, may be coupled to the substrate leading to important responsivity losses‥ The ways of avoiding...
We report on the photoresponse of AlGaN/GaN HEMT to THz radiation of low and high intensity. We show that the response vs. gate bias dependence can be described by the theory of Dyakonov-Shur in the whole range of radiation intensity. Unusual behavior of the photoresponse vs. intensity was observed under laser irradiation: a quadratic increase of the response followed by saturation. We speculate that...
Diffractive optical elements such as hyperbolic lens and quasi-spherical lens converting a divergent terahertz beam into the focal line segment perpendicular to the optical axis was designed. Due to the fact that the length of the line segment was longer than the aperture of the designed elements the non-paraxial approach was used. The structures were designed for the narrowband application as kinoform...
Phenomena of the radiation coupling to the field effect transistors based terahertz detectors is studied. We show that in the case of flat metallic antennas important part of radiation, instead coupling to the transistors, is coupled to the substrate leading to losses. Experimental and theoretical investigations of the responsivity versus substrate thickness are performed. They clearly show how to...
We evaluate the optical performance of the InP heterojunction bipolar transistors (DHBTs) designed for 100 Gbit/s circuit applications as a room temperature detector operating above 1 THz. They can operate far above the frequencies at which they have gain and can still rectify THz current and voltage.
We report on room-temperature detection of sub-terahertz radiation by InP double heterojunction bipolar transistors designed for 100 Gbit/s circuit applications. Maximum responsivity of 250 V/W around 272 GHz were achieved at room-temperature under unbiased base-emitter and base-collector conditions. We show also that these detectors can operate as sensitive broadband THz detectors in THz imaging...
We demonstrate detection of individual pulses of terahertz radiation generated in femtosecond laser systems by InGaAs plasma-wave terahertz detectors. Nonlinearity of the detection mechanism is analyzed experimentally by comparison of saturation effects at femtosecond and nanosecond terahertz excitations. Good sensitivity and wide dynamic range make these detectors promising for short-pulsed terahertz...
We report on room-temperature plasmonic detection of the thermal emission from a black body in the terahertz and mid-infrared domains by dual-grating-gate InAlAs/InGaAs/InP high electron mobility transistors (HEMTs). In such detectors, the asymmetric grating gate of a large area acts as an effective antenna that improves the performance in the two spectral domains.
We report on sub-Terahertz photoconductivity of bulk HgxCd1−xTe crystals with composition close to semiconductor-to-semimetal topological transition. Low magnetic field Shubnikov-de Hass like oscillations were observed with a period which does not depend on the incident frequency. Moreover, anomalous B-periodic oscillations were also observed at higher magnetic fields.
Nanometer size field effect transistors can operate as efficient resonant or broadband terahertz detectors, mixers, phase shifters and frequency multipliers at frequencies far beyond their fundamental cut-of frequency. This work is an overview of some recent results concerning the THz detection by Si MOS transistors with back-gate, low temperatures operation, and circular polarization studies of nanometer...
Two-dimensional electron plasma in nanometer size field effect transistors can oscillate in Terahertz (THz) frequencies, far beyond transistors fundamental cut-of frequencies. We propose an overview of some important and recent results concerning THz detection by nanometer field effect transistors. The subjects were selected in a way to stress some new aspects of the physics of nanometer scale field...
The goal of our work was to study the capability of field effect transistors to measure high power THz radiation at frequencies from 0.1 up to 3 THz and to determine the linear detection limits. We observed different types of the photoresponse dependence on the incident radiation power. We qualitatively explain the unusual sub-linear behavior observed in high intensities.
We present experimental study of terahertz detection by asymmetric dual-grating gate HEMT structures. The separate contributions of the gate leakage current and the loading effect to the rectification signal in the sub-threshold region was investigated versus temperature and frequency range.
We report on resonant and non-resonant (broad-band) detection of terahertz (THz) radiation using Strained-Si MODFETs. The devices were excited at room temperature by two types of THz sources at 0.292 THz and at 1.5 THz. Non-resonant response with maxima around the threshold voltage was observed. Shubnikov-de Haas along with photoresponse measurements were performed simultaneously to demonstrate that...
Terahertz (THz) light helicity sensitive photoresponse in GaAs/AlGaAs high electron mobility transistors and silicon metal oxide semiconductor field effect transistors is reported. The helicity dependent detection mechanism is interpreted as an interference of plasma oscillations in the channel of the field-effect-transistors (generalized Dyakonov-Shur model). The observed helicity dependent photoresponse...
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