We present investigations of the fin-shaped GaN/AlGaN field effect transistors with two lateral Schottky barrier gates exactly placed on the edges of the fin-shaped transistor channel. We call this kind of FinFET modification the EdgeFET. It allowed us to efficiently control the current flow in two-dimensional electron gas conduction channel. We present experimental data of sub-THz detection by EdgeFETs. Control of the side gates allows changing the width of two-dimensional electron gas and forming a wire, as we expect should be beneficial for observation of terahertz plasma wave resonances. This paves the way towards future terahertz optopair using high-quality factor plasma wave resonances, for which it is necessary to eliminate oblique modes. We report also on the high-voltage, noise, and radio frequency (RF) performances of aluminium gallium nitride/gallium nitride (AlGaN/GaN) on silicon carbide (SiC) devices without any GaN buffer. Such a GaN–SiC hybrid material was developed in order to improve thermal management and to reduce trapping effects should be beneficial for observation of resonant emission.
KEYWORDS: Plasma, Field effect transistors, Terahertz radiation, Heterojunctions, Fin field effect transistors, Transistors, Terahertz detection, Gallium nitride, Temperature metrology
We report on the investigations of the fin-shaped GaN/AlGaN field effect transistors with two lateral Schottky barrier gates exactly placed on the edges of the fin-shaped transistor channel. This kind FinFET modification (EdgeFET) allowed us to efficiently control the current flow in two-dimensional electron gas conduction channel. We present experimental data of sub THz detection by EdgeFETs. We describe also how it is beneficial for observation of resonant plasma wave THz detection and emission.
We study optical response of a plasmonic crystal based on multi-gated 2D structure with periodic modulation of the electron density in the device channel. In such a structure, the plasma wave velocity is periodically modulated as well. We consider the simplest model of periodically alternating stripes of the electron density and plasma wave velocity: active regions with high plasma wave velocity and passive regions with low plasma wave velocity. Terahertz radiation applied to such a structure excites plasmonic resonances both in the active and passive stripes. The width of the resonances is determined by the momentum relaxation rate. For sufficiently large relaxation rates, the resonances in the passive regions strongly overlap and only “active resonances” survive. In this regime, the plasmonic oscillations in the active regions exponentially decay into the passive regions, so that different active regions are disconnected at plasmonic frequencies but connected at zero dc frequency. We assume that dc current is applied to this plasmonic crystal and calculate radiation-induced correction to the dissipation in the channel. We demonstrate that with increasing the dc current this correction changes sign, which results in amplification of the optical signal.
We explore current-driven Dirac plasmon dynamics in monolayer graphene metasurfaces. DC-current-induced complete suppression of the graphene absorption is experimentally observed in a broad frequency range followed by a giant amplification (up to ∼ 9 % gain) of an incoming terahertz radiation at room temperature.
We report on the investigations of the fin-shaped GaN/AlGaN field effect transistors (FinFETs) with two lateral Schottky barrier gates exactly placed at the edges of the fin-shaped transistor channel. This kind of FinFET modification (called EdgeFET) allowed us to efficiently control the current flow in two-dimensional electron gas conduction channel. Moreover, due to depletion, regions of the channel at a certain range of reverse bias form a nanowire, which is beneficial for the tunable resonant THz detection. Our studies of current-voltage characteristics and response in the sub-terahertz frequency range confirm the validity of the approach.
Linear and gapless energy spectrum of graphene carriers enables population inversion under optical and electrical pumping. We first theoretically discovered this phenomenon and demonstrated experimental observation of single-mode THz lasing with rather weak intensity at 100K in current-injection pumped graphene-channel field-effect transistors (GFETs). We introduce graphene surface plasmon polariton (SPP) instability to substantially boost the THz gain. We demonstrate our experimental observation of giant amplification of THz radiation at 300K stimulated by graphene plasmon instabilities in asymmetric dual-grating gate (ADGG) GFETs. Integrating the graphene SPP amplifier into a GFET laser will be a promising solution towards room-temperature intense THz lasing.
F. Teppe, S. Ruffenach, S. Krishtopenko, M. Marcinkiewicz, C. Consejo, J. Torres, M. Orlita, W. Knap, D. Smirnov, S. Morozov, V. Gavrilenko, N. Mikhailov, S. Dvoretskii
HgCdTe compounds can be engineered to fabricate “gapped-at-will” structures. Therefore, 1D, 2D and even 3D massless particles can be observed in topological phase transitions driven by intrinsic and external physical parameters. In this work, we report on our experimental results, obtained by temperature-dependent Terahertz and Mid-Infrared magneto-spectroscopy, of topological phase transitions in HgCdTe-based quantum wells and bulk samples. These transitions are accompanied with the appearance of 2D and 3D massless particles called Dirac and Kane fermions, respectively.
This paper addresses the problem of critical operations in Degraded Visual Environment (DVE). DVE usually refer when the perception of a pilot is degraded by environmental factors, including the presence of obscurants from bad weather (e.g. fog, rain, snow) or accidental events (e.g. brownout, whiteout, smoke). Critical operations in DVE are a growing field of research as it is a cause of numerous fatal accidents for operational forces. Due to the lack of efficient sources and sensors in the Terahertz (THz) region, this domain has remained an unexplored part of the electromagnetic spectrum. Recently, the potential use of sub-Terahertz waves has been proposed to see through dense clouds of obscurants (e.g. sand, smoke) in DVE conditions. In order to conduct a performance evaluation of sub-Terahertz systems, several sub-terahertz systems (e.g. bolometer-array cameras, liquid helium cooled bolometers) were operated in artificial controlled DVE conditions at ONERA facilities. The purpose of this paper is to report field experiments results in controlled DVE conditions: attenuation measurements from 400 GHz to 700 GHz with a performance evaluation of different sub-Terahertz systems are presented.
We study theoretically and experimentally the plasmonic THz detection by the asymmetric dual-grating-gate HEMT at room temperature without source-to-drain bias. We derive the analytical expressions of photocurrents due to the plasmonic drag and ratchet effects, and we discuss about their frequency dependences. We also compare the theory to the experimentally obtained frequency dependence. It is demonstrated that they agree qualitatively well.
Ignas Grigelionis, Marcin Białek, Marian Grynberg, Magdalena Czapkiewicz, Valery Kolkovskiy, Maciej Wiater, Tomasz Wojciechowski, Jerzy Wróbel, Tomasz Wojtowicz, Nina Diakonova, Wojciech Knap, Jerzy Łusakowski
To understand a terahertz (THz) response of a point contact device, a number of samples based on CdTe/CdMgTe quantum wells grown by a molecular beam epitaxy were investigated at low temperatures and high magnetic fields. The experiments involved magneto-transport, photocurrent, and transmission measurements carried out with monochromatic THz sources or a Fourier spectrometer. Samples of different geometry with and without gate metallization were used. We observed excitations of a two-dimensional electron plasma in the form of optically induced Shubnikov-de Haas oscillations, cyclotron resonance transitions, and magneto-plasmon resonances. A polaron effect was observed at magnetic fields higher than 10 T. A point contact device processed with an electron beam lithography was investigated as a detector of THz radiation. It was shown that the main mechanism responsible for a THz performance of the point contact was excitation of magneto-plasmons with a wavevector defined by geometrical constrictions of the device mesa.
I. Grigelionis, M. Bialek, M. Grynberg, M. Czapkiewicz, V. Kolkovski, M. Wiater, M. Wojciechowski, J. Wróbel, T. Wojtowicz, N. Diakonova, W. Knap, J. Łusakowski
THz response of a number of samples based on CdTe/CdMgTe quantum wells grown by a molecular beam epitaxy was investigated at low temperatures and high magnetic fields. The experiments involved magnetotransport, photocurrent, and transmission measurements carried out with a monochromatic THz sources or a Fourier spectrometer. Samples of different geometry, with and without a gate metallization were used. We observed excitations of a two-dimensional plasma in the form of optically-induced Shubnikov-de Haas oscillations, cyclotron resonance transitions and magnetoplasmon resonances. A polaron effect was observed at magnetic fields higher than 10 T. A point contact device processed with an electron beam lithography was investigated as a detector of THz radiation. It was shown that the main mechanism responsible for a THz performance of the point contact was excitation of magnetoplasmons with a wave vector defined by geometrical constrictions of the device mesa.
We report on the development of a novel class of nanowire-based THz detectors in which the field effect transistor (FET) is integrated in a narrow-band antenna. When the THz field is applied between the gate and the source terminals of the FET, a constant source-to-drain photovoltage appears as a result of the non-linear transfer characteristic of the transistor. In order to achieve attoFarad-order capacitance we fabricate lateral gate FET with gate widths smaller than 100 nm. Our devices show a maximum responsivity of 110 V/W without amplification, with noise equivalent power levels ≤ 1 nW/√Hz at room temperature. The 0.3 THz resonant antenna has bandwidth of ~ 10 GHz and opens a path to novel applications of our technology including metrology, spectroscopy, homeland security, biomedical and pharmaceutical applications. Moreover the possibility to extend this approach to relatively large multi-pixel arrays coupled with THz sources makes it highly appealing for a future generation of THz detectors.
The recent advances in emission and detection of terahertz radiation using two-dimensional (2-D) plasmons in semiconductor nanoheterostructures for nondestructive evaluations are reviewed. The 2-D plasmon resonance is introduced as the operation principle for broadband emission and detection of terahertz radiation. The device structure is based on a high-electron-mobility transistor and incorporates the authors’ original asymmetrically interdigitated dual-grating gates. Excellent THz emission and detection performances are experimentally demonstrated by using InAlAs/InGaAs/InP and/or InGaP/InGaAs/GaAs heterostructure material systems. Their applications to nondestructive material evaluation based on THz imaging are also presented.
We report on a Terahertz magnetospectroscopy study of a set of five HgTe quantum wells of different thickness, from below to above the critical thickness dc. In quantizing magnetic fields up to 11 T, both intraband and interband transitions have been observed. In samples with inverted band structures, we confirm the observation of the crossing avoiding of the zero-mode Landau levels at a critical value of the magnetic field. In samples with non-inverted band structures, close to the critical thickness, we report on the square root dependence of the intraband transition energy on the magnetic field, as expected in the single-particle model of massless Dirac fermions. The obtained results are compared with the allowed transition energies calculated using the 8 × 8 Kane model.
Field effect transistors are promising detectors of THz radiation. They operate at room temperatures have high responsivity, low noise equivalent power, and fast response time. However, their linearity (dynamic range) and possibility of their application in the domain of high power radiation has not been yet sufficiently studied. We have investigated room temperature field effect transistors, detection at frequencies from 0.3 to 3 THz with power up to 100 kW/cm2. Several types of HEMTs and MOSFETs operating in the broadband non resonant detection regime, have been investigated. To provide a wide range of incident THz radiation intensities we used continuous-wave and pulsed sources: backward oscillators, CO2 pumped methanol laser, free electron laser, NH3, D2O, and CH3F lasers. We find that the photoresponse of HEMTs and MOSFETs is linear in radiation intensity up to a several kW/cm2 and then it saturates. The onset of the saturation depends on the radiation frequency and the transistor type. The observed saturation behavior can not be explained by the existing theoretical model which predict a square root like dependence of the photoresponse. We tentatively attribute the unusual features of the photoresponse saturation observed at high intensities considering high electric field transport phenomena, e.g., electron heating and electron velocity saturation.
K. Romanov, N. Dyakonova, D. But, F. Teppe, W. Knap, M. Dyakonov, C. Drexler, P. Olbrich, J. Karch, M. Schafberger, S. Ganichev, Yu. Mityagin, O. Klimenko
We use two antenna model to develop a theory of the recently observed helicity-sensitive detection of terahertz radiation by FETs. The effect is due to the mixing of the ac signals produced in the channel by the two antennas. We obtain the helicity-dependent part of the photoresponse and its dependence on the antenna impedance, gate length, and gate voltage.
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 low temperatures operation, linearity, and circular polarization studies of
nanometer scale field effect transistors for the detection of terahertz radiation. Also first results on graphene transistors
are discussed.
This paper reviews recent advances in emission and detection of terahertz radiation using two dimensional (2D) plasmons in semiconductor nano-heterostructures for nondestructive evaluations. The 2D plasmon resonance is introduced as the operation principle for broadband emission and detection of terahertz radiation. The device structure is based on a high-electron mobility transistor and incorporates the authors’ original asymmetrically interdigitated dual grating gates. Excellent terahertz emission and detection performances are experimentally demonstrated by using InAlAs/InGaAs/InP and/or InGaP/InGaAs/GaAs heterostructure material systems. Their applications to nondestructive material evaluation based on terahertz imaging are also presented.
A. Penot, J. Torres, P. Nouvel, L. Varani, F. Teppe, C. Consejo, N. Dyakonova, W. Knap, Y. Cordier, S. Chenot, M. Chmielowska, J.-P. Faurie, B. Beaumont, P. Shiktorov, E. Starikov, V. Gruzinskis
Emission of terahertz (THz) radiations from interdigitated GaN quantum-wells structures under DC-bias has
been measured at room temperature. This measurements has been performed by a 4K Si-Bolometer associated
with a Fourier Transform Spectrometer. Using an analytical model, we have shown that the observed peak
at approximately 3 THz due to 2D ungated plasma-waves oscillations in the quantum well, is emitted by the
metallic contacts of our device acting as antennas.
We present the realization of high electron mobility transistors on GaN-heterostructures usable for mixing and rectification in the THz range. Device fabrication is fully compatible with industrial processes employed for millimetre wave integrated circuits. On-chip, integrated, polarization-sensitive, planar antennas were designed to allow selective coupling of THz radiation to the three terminals of field effect transistors in order to explore different mixing schemes for frequencies well above the cutoff frequency for amplification. The polarization dependence of the spectral response in the 0.18-0.40 THz range clearly demonstrated the possible use as integrated heterodyne mixers.
Semiconductor nanowires (NWs) represent an ideal building block for implementing rectifying diodes or plasma wave detectors that could operate well into the THz, thanks to the typical attofarad-order capacitance. Despite the strong effort in developing these nanostructures for a new generation of complementary metal-oxide semi conductors (CMOS), memory and photonic devices, their potential as radiation sensors into the Terahertz is just starting to be explored. We report on the development of NW-based field effect transistors operating as high sensitivity THz detectors in the 0.3 - 2.8 THz range. By feeding the radiation field of either an electronic THz
source or a quantum cascade laser (QCL) at the gate-source electrodes by means of a wide band dipole antenna, we measured a photovoltage signal corresponding to responsivity values up to 100 V IW, with impressive noise equivalent power levels < 6 x 10-11W/Hz at room temperature and a > 300kHz modulation bandwidth. The potential scalability to even higher frequencies and the technological feasibility of realizing multi-pixel arrays coupled with QCL sources make the proposed technology highly competitive for a future generation of THz detection systems.
The concept of THz detection based on excitation of plasma waves in two-dimensional electron gas in Si FETs is
one of the most attractive ones, as it makes possible the development of the large-scale integrated devices based
on a conventional microelectronic technology including on-chip antennas and readout devices integration. In this
work we report on investigations of Terahertz detectors based on low-cost silicon technology field effect
transistors and asymmetric unit cell double grating gate field effect transistor. Double-grating-gate field-effect
transistors have a great potential as terahertz detectors. This is because the double grating gate serves not only for
carrier density tuning but also as an efficient THz radiation coupler. In this paper, we present characterization of
these transistors using high magnetic fields. Low and high magnetic field data are used to determine the electron
mobility and electron concentration, respectively, in different parts of the transistor channel. We show that
detectors, consisting of a coupling antenna and a n-MOS field effect transistor as rectifying element, are efficient
for THz detection and imaging. We demonstrate that in the atmospheric window around 300 GHz, these detectors
can achieve a record noise equivalent power below 10 pW/Hz0.5 and responsivity above 90 kV/W once integrated
with on-chip amplifier. We show also that they can be used in a very wide frequency range: from ~0.2 THz up to
1.1 THz. THz detection by Si FETs paves the way towards high sensitivity silicon technology based focal plane
arrays for THz imaging.
We report about fabrication and characterization of semiconductor nanowire-based field effect transistor devices
which can act as detectors for electromagnetic radiation in the THz frequency range. The detection mechanism
is based on the nonlinear transfer characteristic of the transistor, which is used to realize signal rectification; the
small capacitance related to the nanowire small cross section is beneficial in allowing a good device sensitivity
up to 1.5 THz at room temperature. Due to the extreme flexibility with which semiconductor nanowires can be
grown, we discuss how the basic, homogeneous InAs or InSb nanowire FETs can be improved to realize smarter
devices and functionalities.
We report on ultrahigh sensitive, broadband terahertz (THz) detectors based on asymmetric double-grating-gate (A-DGG)
high electron mobility transistors, demonstrating a record responsivity of 2.2 kV/W at 1 THz with a superior low
noise equivalent power of 15 pW/√Hz using InGaAs/InAlAs/InP material systems. When THz radiation is absorbed
strong THz photocurrent is first generated by the nonlinearity of the plasmon modes resonantly excited in undepleted
portions of the 2D electron channel under the high-biased sub-grating of the A-DGG, then the THz photovoltaic response
is read out at high-impedance parts of 2D channel under the other sub-grating biased at the level close to the threshold.
Extraordinary enhancement by more than two orders of magnitude of the responsivity is verified with respect to that for
a symmetric DGG structure.
We report on measurements of radiation transmission in the 0.220-0.325 THz and 0.75-1.1 THz
frequency ranges through GaN quantum wells grown on sapphire substrates at nitrogen and room
temperatures. Significant enhancement of the transmitted beam intensity with applied voltage is
found at nitrogen temperature. This effect is explained by changes in the mobility of two-dimensional
electrons under electric bias. We have clarified which physical mechanism modifies the electron mobility
and we suggest that the effect of voltage-controlled sub-terahertz transmission can be used for
the development of electro-optic modulators operating in the sub-THz frequency range.
III-Nitride semiconductors are promising nonlinear materials for optical wavelength conversion. However second
harmonic generation in bulk GaN is weak because GaN is strongly dispersive. We show that appropriate photonic crystal
patterning in GaN helps to overcome dispersion and provides quasi-phase matching conditions, resulting in substantially
increased conversion efficiency obtained in a flexible manner. Enhancement factors of more than five orders of
magnitude can be achieved. Use of photonic crystals makes it possible to reduce the effective observation volume,
thereby opening new opportunities such as the study of single-molecule dynamics, even in high concentration solutions.
We have demonstrated sharp enhancement of the fluorescence of single molecules immobilized on the surface of a GaN
photonic crysta,l when the molecules are excited via the resonant second harmonic generation process.
AlGaN/GaN based FETs have great potential as sensitive and fast operating detectors because of their material
advantages such as high breakdown voltage, high electron mobility, and high saturation velocity. These advantages could
be exploited for resonant and non-resonant terahertz detection. We have designed, fabricated, and characterized
AlGaN/GaN based FETs as single pixel terahertz detectors. This work focuses on non-resonant detection and imaging
using GaN field plate FETs. To evaluate their performances as terahertz detectors, we have measured the responsivity as
a function of gate voltage, the azimuthal angle between the terahertz electric field, the source-to-drain direction, and the
temperature. A simple analytical model of the response is developed. It is based on plasma density perturbation in the
transistor channel by the incoming terahertz radiation. The model shows how the non-resonant detection signal is related
to static (dc) transistor characteristics and it fully describes the experimental results on the non-resonant sub-terahertz
detection by the AlGaN/GaN based FETs. The imaging performances are evaluated by scanning objects in transmission
mode and an example of application of terahertz imaging as new non-destructive technique for the quality control of
materials is given. Results indicate that these FETs can be considered as promising devices for terahertz detection and
imaging applications.
Self-assembled nanowires represent a new interesting technology to be explored in order to increase the cut-off
frequency of electronic THz detectors. They can be developed in field effect transistor (FET) and diode geometries
exploiting non-linearities of either the transconductance or the current-voltage characteristic as detection mechanism. In
this work we demonstrate that semiconductor nanowires can be used as building blocks for the realization of highsensitivity
terahertz one-dimensional FET detectors. In order to take advantage of the low effective mass and high
mobilities achievable in III-V compounds, we have used InAs nanowires, grown by vapor-phase epitaxy, and properly
doped with selenium to control the charge density and to optimize source-drain and contact resistance. The detection
mechanism exploits the non-linearity of the transconductance: the THz radiation field is fed at the gate-source electrodes
with wide band antennas, and the rectified signal is then read at the drain output in the form of a DC voltage.
Responsivity values as large as 1 V/W at 0.3 THz have been obtained, with noise equivalent powers (NEP) < 2 × 10-9
W/√Hz at room temperature. The large existing margins for technology improvements, the scalability to higher
frequencies, and the possibility of realizing multi-pixel arrays, make these devices highly competitive as a future
solution for THz detection.
W. Knap, F. Teppe, C. Consejo, B. Chenaud, J. Torres, P. Solignac, Z. Wasilewski, M. Zholudev, N. Dyakonova, D. Coquillat, P. Buzatu, A. El Fatimy, F. Schuster, H. Videlier, M. Sakowicz, B. Giffard, T. Skotnicki, F. Palma
In this work we review the most important results concerning the physics and applications of FETs as Terahertz
detectors. We present two experiments showing: i) Terahertz detection based on low cost 130 nm silicon
technology Field Effect Transistors in the sub-THz range (0.2 THz up to 1.1 THz) and ii) first results on
detection by FETs of emission from 3.1 THz Quantum Cascade Lasers.
In this work, the performance of InP-based HEMTs as a THz detector was experimentally studied. The nature
of the THz rectification by the two-dimensional plasmons in which the DC drain current variation ΔId becomes
maximal around the threshold voltage was observed. Based on the imaging measurement, it was confirmed
that our HEMTs device can work for sensitive THz imaging at 0.3 THz. The directivity of the detector was
characterized with the maximum responsivity of 26.1 V/W at θ = 160 degrees.
We report on active imaging with CMOS transistors at 300 GHz and 1.05 THz. Two basic focal plane arrays consisting
of nMOS transistors and wide-band bow-tie antennas have been implemented in a low-cost 130 nm CMOS technology.
Raster scan imaging of objects concealed in a paper envelope has been achieved at 300 GHz with a commercial radiation
source. The images clearly reveal the concealed objects with a dynamic range of 35 dB and a resolution of 3 mm. At
1.05 THz, the pixels achieve a responsivity of 50 V/W and a noise equivalent power of 900 pW/Hz0.5.
This paper reviews recent advances in emission and detection of terahertz (THz) radiation utilizing two-dimensional
plasmons in semiconductor heterostructures and their possible sensing and spectroscopic applications. The device is
introduced as a light source into a Fourier-transform THz spectrometer. Water-vapor absorption lines as well as
fingerprints of honey and maple syrup of sugar-group materials were successfully observed. Absolute sensitivity
characteristics and detection polarization are also presented, showing the possibility of new highly efficient THz
detectors.
We investigated the emission of terahertz radiation from a doubly interdigitated grating gates high electron mobility transistor. The experiment was performed using Fourier spectrometer system coupled with high sensitive 4 K Silicon bolometer under the vacuum. The observed emission was explained as due to the excitation of the plasma waves by means of hot 2D plasmons. We also investigated the optical stimulation of the plasma waves by subjecting the device to a CW 1.5 µm laser beam. Dependence of the emission on the gate bias (i.e. on electron density) was observed and interpreted as due to the self oscillation of the plasma waves.
The I-V characteristics of GaN/AlGaN HFET and 1/f noise at 4K have been measured in strong magnetic fields, where the electron mobility is affected by geometric magnetoresistance. The magnetic field dependence of the 1/f noise shows that the number of electrons fluctuations is the dominant mechanism of the 1/f noise and precludes the mobility fluctuations mechanism. The channel mobility extracted from the magnetoresistance data first increases with gate bias reaching the maximum value of ~(0.9-1.0) m2/Vs at the 2D electron concentration of 5x1012 cm-2. This maximum value is close to the estimated ballistic mobility limit of 1.2 m2/Vs determined by the electron transit time with the Fermi velocity.
The way how to make spectroscopy in the far infrared by replacing mechanical spectral elements(moving mirrors or gratings) by superconducting solenoids is shown. The magnetic field changes the FIRproperties of the semiconductors through the cyclotron resonance or the Zeeman effect allowing to makespectroscopy in the range 35cm-1 - 160cm-1 with the resolution up to 0.3cm-1. We present the possibilities andlimits of the spectroscopy which uses a magnetic field to scan (tune) the characteristic energies of the narrowband spectral elements: sources, filters and detectors. All described below devices work immersed in theliquid helium bath. Therefore spectroscopy based on magnetically tunable narrow band elements provides alsoultralow background radiation conditions for measurements.
Emission of FIR due to radiative recombination between shallow impurities states inselectively doped multiquantum wells (MQW) is studied as a function of electric and magneticfields applied to the structure. It allows to propose the efficient FIR sources for tests ofbolometers working in millikelvin temperatures.
Cyclotron emission sources of the far infrared radiation have unique features to be continuously (magnetic field) tuned and narrow band ones [1],[2]. We show practical realization and examples of application of the transmission spectrometer based on the bulk GaAs and InSb cyclotron resonance sources.
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