Abstract-Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons

D. B. But, M. Mittendorff, C. Consejo, F. Teppe, N. N. Mikhailov, S. A. Dvoretskii, C. Faugeras, S. Winnerl, M. Helm, W. Knap, M. Potemski & M. Orlita

https://www.nature.com/articles/s41566-019-0496-1

The Landau level laser was proposed long ago as a unique source of monochromatic radiation that would be widely tunable in the THz and infrared spectral ranges using a magnetic field. However, despite many efforts, this appealing concept never progressed to the design of a reliable device. This is because of the efficient Auger scattering of Landau-quantized electrons, an intrinsic non-radiative recombination channel that eventually gains over cyclotron emission in all materials studied so far (conventional semiconductors with parabolic bands, but also in graphene with massless electrons). Auger processes are favoured in these systems because the Landau levels (or their subsets) are equally spaced in energy. Here, we show that this scheme does not apply to massless Kane electrons in gapless HgCdTe, where undesirable Auger scattering is strongly suppressed and sizeable cyclotron emission is observed. The gapless HgCdTe thus appears as a material of choice for future Landau level lasers.

Abstract-Terahertz Spectroscopy of Two-Dimensional Semimetal in Three-Layer InAs/GaSb/InAs Quantum Well

S. S. Krishtopenko, S. Ruffenach, F. Gonzalez-Posada, C. Consejo, W. Desrat, B. Jouault, W. Knap, M. A. Fadeev, A. M. Kadykov, V. V. Rumyantsev, S. V. Morozov, G. Boissier, E. Tournié, V. I. Gavrilenko, F. Teppe

https://link.springer.com/article/10.1134%2FS0021364019020085

The features of terahertz photoluminescence and magnetoabsorption in magnetic fields up to 16 T in threelayer InAs/GaSb/InAs quantum wells with a band structure corresponding to a “two-dimensional semimetal” are studied. The comparison of the positions and amplitudes of the photoluminescence lines with the theoretical calculations of oscillator strengths for interband and intraband transitions performed using the eight-band Kane Hamiltonian indicates the existence of a nonradiative recombination channel associated with the overlap of the conduction and valence bands. The energies of interband and intraband Landau level transitions observed in the magnetoabsorption spectra are in good agreement with theoretical calculations, which confirms the predicted band structure.

Abstract-Field effect transistors for terahertz applications

W. Knap, M.I. Dyakonov,

https://www.sciencedirect.com/science/article/pii/B9780857092359500057

This chapter gives an overview of the main physical ideas and experimental results concerning the application of field effect transistors (FETs) for the generation and detection of terahertz (THz) radiation. Resonant frequencies of the two-dimensional plasma oscillations in FETs increase with the reduction of the channel dimensions and for submicron gate length reach the THz range. When the mobility is high enough, the dynamics of a short channel FET at THz frequencies is dominated by plasma waves. This may result, on the one hand, in a direct current (dc) induced spontaneous generation of plasma waves and THZ emission and, on the other hand, in a resonant photoresponse to incoming radiation. In other cases, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector.

Abstract-Handbook of Terahertz Technology for Imaging, Sensing and Communications

W. Knap, M.I. Dyakonov,

https://www.sciencedirect.com/science/article/pii/B9780857092359500057

This chapter gives an overview of the main physical ideas and experimental results concerning the application of field effect transistors (FETs) for the generation and detection of terahertz (THz) radiation. Resonant frequencies of the two-dimensional plasma oscillations in FETs increase with the reduction of the channel dimensions and for submicron gate length reach the THz range. When the mobility is high enough, the dynamics of a short channel FET at THz frequencies is dominated by plasma waves. This may result, on the one hand, in a direct current (dc) induced spontaneous generation of plasma waves and THZ emission and, on the other hand, in a resonant photoresponse to incoming radiation. In other cases, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector.

Abstract-Reducing noise equivalent power in InP DHBT terahertz detector by biasing the collector

 N. Dyakonova,  D. Coquillat,   D. But,  C. Consejo, F. Teppe, W. Knap,  L. Varani,  S. Blin,  V. Nodjiadjim,   A. Konczy,

http://ieeexplore.ieee.org/document/7986010/


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.

Abstract-Two-dimensional plasmons in lateral carbon nanotube network structures and their effect on the terahertz radiation detection

V. Ryzhii, T. Otsuji, M. Ryzhii, V. G. Leiman, G. Fedorov, G. N. Goltzman, I. A. Gayduchenko, N. Titova, D. Coquillat, D. But, W. Knap, V. Mitin, M. S. Shur

(Submitted on 17 Feb 2016)

http://arxiv.org/abs/1602.05306

We consider the carrier transport and plasmonic phenomena in the lateral carbon nanotube (CNT) networks forming the device channel with asymmetric electrodes. One electrode is the Ohmic contact to the CNT network and the another contact is the Schottky contact. These structures can serve as detectors of the terahertz (THz) radiation. We develop the device model for response of the lateral CNT networks which comprise a mixture of randomly oriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The proposed model includes the concept of the two-dimensional plasmons in relatively dense networks of randomly oriented CNTs (CNT "felt") and predicts the detector responsivity spectral characteristics. The detection mechanism is the rectification of the ac current due the nonlinearity of the Schottky contact current-voltage characteristics under the conditions of a strong enhancement of the potential drop at this contact associated with the plasmon excitation. We demonstrate that the excitation of the two-dimensional plasmons by incoming THz radiation the detector responsivity can induce sharp resonant peaks of the detector responsivity at the signal frequencies corresponding to the plasmonic resonances. The detector responsivity depends on the fractions of the s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or destruction of these CNTs leads to a marked increase in the responsivity in agreement with our experimental data. The resonant THz detectors with sufficiently dense lateral CNT networks can compete and surpass other THz detectors using plasmonic effects at room temperatures.

Abstract-Silicon junctionless field effect transistors as room temperature terahertz detectors

J. Marczewski^1,a), W. Knap^2,3, D. Tomaszewski¹, M. Zaborowski¹ and P. Zagrajek⁴
 HIDE AFFILIATIONS
1 Institute of Electron Technology, al. Lotnikow 32/46, 02-668 Warsaw, Poland
2 Institute of High Pressure Physics of the Polish Academy of Sciences, ul. Sokolowska 29/37, 01-142 Warsaw, Poland
3 Laboratory Charles Coulomb, Montpellier University & CNRS, Place E. Bataillon, Montpellier 34095, France
4 Institute of Optoelectronics, Military University of Technology, ul. gen. S. Kaliskiego 2, 00-908 Warsaw, Poland
a) Author to whom correspondence should be addressed. Electronic mail: jmarcz@ite.waw.pl
J. Appl. Phys. 118, 104502 (2015); http://dx.doi.org/10.1063/1.4929967
http://scitation.aip.org/content/aip/journal/jap/118/10/10.1063/1.4929967

Terahertz (THz) radiation detection by junctionless metal-oxide-semiconductor field-effect transistors (JL MOSFETs) was studied and compared with THz detection using conventionalMOSFETs. It has been shown that in contrast to the behavior of standard transistors, the junctionless devices have a significant responsivity also in the open channel (low resistance) state. The responsivity for a photolithographically defined JL FET was 70 V/W and the noise equivalent power 460 pW/√Hz. Working in the open channel state may be advantageous for THz wireless and imaging applications because of its low thermal noise and possible high operating speed or large bandwidth. It has been proven that the junctionless MOSFETs can also operate in a zero gate bias mode, which enables simplification of the THz array circuitry. Existing models of THz detection by MOSFETs were considered and it has been demonstrated that the process of detection by these junctionless devices cannot be explained within the framework of the commonly accepted models and therefore requires a new theoretical approach.

Abstract-3-D-Printed Flat Optics for THz Linear Scanners

Suszek, J. Siemion, A. ; Bieda, M.S. ; Blocki, N. ; Coquillat, D. ; Cywinski, G. ; Czerwinska, E. ; Doch, M. ;Kowalczyk, A. ; Palka, N. ; Sobczyk, A. ; Zagrajek, P. ; Zaremba, M. ; Kolodziejczyk, A. ; Knap, W. ;Sypek, M.
http://ieeexplore.ieee.org/xpl/abstractAuthors.jsp?tp=&arnumber=7036140&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D7036140

THz beam shaping via a single diffractive optical element is used to convert a divergent beam into a focal line segment perpendicular to the optical axis. The novel structure was designed for narrowband applications as a kinoform element and we successfully applied it in active, high-speed, THz linear scanners. The theoretical approach and experimental results are presented.

Abstract-Terahertz photodetectors based on tapered semiconductor nanowires

L. Romeo¹, D. Coquillat², E. Husanu¹, D. Ercolani¹, A. Tredicucci³, F. Beltram¹, L. Sorba¹, W. Knap² and M. S. Vitiello^1,a)
 HIDE AFFILIATIONS
1 NEST, Scuola Normale Superiore and CNR—Istituto Nanoscienze, Piazza San Silvestro 12, I-56127 Pisa, Italy
2 Laboratoire Charles Coulomb, UMR 5221 CNRS-Universite' Montpellier 2, 34095 Montpellier, France
3 Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3 and NEST, CNR - Istituto Nanoscienze, 56127 Pisa, Italy
a) miriam.vitiello@sns.it
Appl. Phys. Lett. 105, 231112 (2014); http://dx.doi.org/10.1063/1.4903473

http://scitation.aip.org/content/aip/journal/apl/105/23/10.1063/1.4903473?showFTTab=true&containerItemId=content/aip/journal/apl

We report on the demonstration of Terahertz (THz) broadband detectors based on field effect transistors exploiting tapered semiconductor nanowires. The intrinsic asymmetry provided by the nanowires geometry allows to achieve responsivity values as high as 55 V/W (2.5 mA/W) and a noise-equivalent-power of 3 × 10⁻¹⁰ W/Hz^1/2 independent of the specific gate voltage applied. The possibility to reduce the number of terminals required to the source and drain contacts only and the technological feasibility of multi-pixel arrays are promising for the realization of compact and integrated THz matrix array detection systems.

Abstract-Performance Limits for Field Effect Transistors as Terahertz Detectors

V. Yu. Kachorovskii, S. L. Rumyantsev, W. Knap, M. Shur
http://arxiv.org/abs/1302.7089

We present estimates of the performance limits of terahertz detectors based on the field effect transistors (FET) in the regime of broadband detection. The maximal responsivity is predicted for short-channel FETs in the subthreshold regime. We also calculate the conversion efficiency Q of the device defined as the ratio of the power dissipated by radiation-induced dc current to the THz dissipated power. We show that Q has an absolute maximum as a function of two variables: the power and the frequency of the incoming radiation. The maximal value of Q is on the order of 10%

Abstract-Graphene field-effect transistors as room-temperature terahertz detectors

http://graphenetimes.com/2012/09/graphene-field-effect-transistors-as-room-temperature-terahertz-detectors-2/

Authors: L. Vicarelli, M. S. Vitiello, D. Coquillat, A. Lombardo, A. C. Ferrari, W. Knap, M. Polini, V. Pellegrini A. Tredicucci

The unique optoelectronic properties of graphene make it an ideal platform for a variety of photonic applications, including fast photodetectors, transparent electrodes in displays and photovoltaic modules, optical modulators, plasmonic devices, microcavities, and ultra-fast lasers. Owing to its high carrier mobility, gapless spectrum and frequency-independent absorption, graphene is a very promising material for the development of detectors and modulators operating in the terahertz region of the electromagnetic spectrum (wavelengths in the hundreds of micrometres), still severely lacking in terms of solid-state devices. Here we demonstrate terahertz detectors based on antenna-coupled graphene field-effect transistors. These exploit the nonlinear response to the oscillating radiation field at the gate electrode, with contributions of thermoelectric and photoconductive origin. We demonstrate room temperature operation at 0.3 THz, showing that our devices can already be used in realistic settings, enabling large-area, fast imaging of macroscopic samples.

Nature Materials. doi:10.1038/nmat3417