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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.
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...
Fabrication and experimental tests of materials and optics for Terahertz range used in field effect transistor detectors arrays are described. The method using diffractive optics, fabricated in 3D printing technology, was used for tests with GaN/AlGaN based FETs sub-THz detectors working in 300 GHz atmospheric window. The lens arrays focus energy exactly on the detectors and additionally reduce mutual...
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...
We present results of improvement of THz images registered at the frequency of 300 GHz. The improvement is achieved by processing of both phase and magnitude information provided by lock-in amplifier. The active imager uses a continuous-wave tunable radiation source. We investigate capabilities of utilizing phase and intensity information in order to obtain more accurate shape of object. Results of...
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 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...
Transistors are possible THz detectors using rectification in the channel that can be applied for detection of high data-rate wireless communications, based on THz-frequency carrier. For the first time, we present the transmission of pseudo-random bit sequence at 0.2 THz using a commercial GaAs transistor and demonstrate open eye patterns up to 0.250 Gbps.
Antenna-coupled field effect transistors have been developed as plasma-wave THz detectors in both InAs nanowire and graphene channel materials. Room temperature operation has been achieved up to 3 THz, with noise equivalent power levels < 10−10 W/Hz1/2, and high-speed response already suitable for large area THz imaging applications.
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 terahertz wireless communication experiments at 0.2 THz, using a commercial GaAs field-effect-transistor as detector. For the first time, we will present the transmission of pseudo-random bit sequence at 0.2 THz using this commercial transistor and demonstrate open eye-patterns up to 1.5 Gbps. This transistor is integrated into a machined horn, so that its sensitivity is improved to 1...
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...
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