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  1. 40 Acta Physica Polonica A

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  5. 9 2008

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  1. 12 Shiktorov P.

  2. 12 Starikov E.

  3. 11 Gružinskis V.

  4. 8 Varani L.

  5. 6 Reggiani L.

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1
Publication available in full text mode
Content available

Asymmetrically Shaped Pseudomorphic Modulation Doped Structure for Microwave Detection

100%
Kozič A., Paškevič Č., Sužiedėlis A., Gradauskas J., Ašmontas S., Szerling A., Wrzesińska H.
Acta Physica Polonica A
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2006
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vol. 110
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issue 6
845-849
EN
In this paper we propose a microwave detector based on a AlGaAs/InGaAs/GaAs structure. Its operation relies on non-uniform carrier heating of the two-dimensional electron gas in the microwave electric fields which is a result of the asymmetric shape of the device fabricated on the base of pseudomorphic modulation doped AlGaAs/InGaAs/GaAs structure. The voltage sensitivity of the device at nitrogen temperature is 38 V/W for 10 GHz radiations and is higher compared to that of modulation doped AlGaAs/GaAs of the same configuration.
2
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Magnetoconductivity of GaAs Transistors as Detectors of THz Radiation

100%
Łusakowski J., Knap W., Kamińska E., Piotrowska A., Gavrilenko V.
Acta Physica Polonica A
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2003
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vol. 103
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issue 6
545-551
EN
Magnetotransport characterisation of field effect transistors processed on GaAs/GaAlAs heterostructure was done at 4.2 K for magnetic fields (B) up to 7 T. Three field effect transistors were processed on a single dice and differed by the length (L) of the gate. Electron mobility (μ) in field effect transistors was estimated from dependence of transistor's conductivity vs. B. The results show a decrease inμ with decreasing L that suggests that scattering by edges of the gated part of a transistor limits the electron mobility. Quality factor (Q) of transistors as resonant detectors of THz radiation was calculated. A high value of Q shows that such field effect transistors with sub-micron L are promising devices that can operate at THz frequencies.
3
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Small-Signal Characterization of FET/HEMT for Terahertz Applications

100%
Starikov E., Shiktorov P., Gružinskis V., Marinchio H., Nouvel P., Torres J., Palermo C., Chusseau L., Varani L., Ziadé P.
Acta Physica Polonica A
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2011
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vol. 119
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issue 2
203-205
EN
Calculations of the small-signal response of InGaAs HEMTs by using the hydrodynamic approach coupled with a pseudo-2D Poisson equation are performed. The spectra of small-signal admittance and impedance are found to demonstrate series of the resonant peaks corresponding to excitation of plasma waves. Possibilities and conditions of instability onset and THz signal detection are discussed.
4
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Monte Carlo Simulation of Noise and THz Generation in InP FET at Excess of Electrons in Channel

100%
Gružinskis V., Shiktorov P., Starikov E.
Acta Physica Polonica A
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2011
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vol. 119
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issue 2
215-217
EN
Electron transport and drain current noise in field effect transistor with n^+ nn^+ InP channel have been studied by Monte Carlo particle simulation which simultaneously solves the Boltzmann transport and pseudo-2D Poisson equations. It is shown that at gate voltages giving excess electron concentration in n-region of channel the drain current self-oscillations in THz frequency range are possible. The self-oscillations are driven by electron plasma instability.
5
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Modeling of THz-Electro-Optical Sampling Measurements

100%
Shiktorov P., Starikov E., Gružinskis V., Varani L., Reggiani L.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
913-916
EN
We carry out a theoretical analysis of THz-electro-optical sampling experimental technique applied to semiconductor structures. The difficulties/impossibility of determining the small-signal conductivity spectrum in the framework of such a technique are analyzed and discussed.
6
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Small and Large Signal Analysis of Terahertz Generation from InN n^+nn^+ Structures with Free-Carrier Grating

100%
Gružinskis V., Shiktorov P., Starikov E.
Acta Physica Polonica A
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2005
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vol. 107
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issue 1
163-168
EN
Electron transport in long (up to 15μm) InN n^+nn^+ structures is theoretically investigated by the Monte Carlo particle technique at low lattice temperatures when optical phonon emission is the dominating scattering mechanism. It is shown that at constant bias a free-carrier grating can be formed inside the n-region. Such a grating is found to be responsible for microwave power generation in the THz frequency range. The generation mechanism is similar to that in submicron n^+nn^+ structures under quasiballistic transport conditions.
7
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Terahertz Emission from the Surfaces of InAs and Other Narrow-Gap Semiconductors

80%
Adomavičius R., Krotkus A., Molis G., Urbanowicz A., Malevich V.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
859-862
EN
THz pulses were used to investigate carrier dynamics in narrow-gap semiconductors. The measurement of the optically induced THz pulse absorption transients provided important insights into electron energy relaxation in the conduction band. In the second set of experiments, THz generation from the surfaces of various semiconductors was studied and compared. It was found that the most efficient THz emitters are semiconductors with a narrow band gap, large intervalley separation in the conduction band, and low nonparabolicity of the main valley.
8
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Efficient Terahertz Pulse Generation in Laser-Induced Gas Plasmas

80%
Löffler T., Kress M., Thomson M., Roskos H.
Acta Physica Polonica A
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2005
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vol. 107
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issue 1
99-108
EN
In this contribution, we review the development of sources for far-infrared (terahertz) radiation based on laser-generated gas plasmas. We describe several generation mechanisms based on ponderomotive forces, external field screening, and optical second-harmonic biasing. These methods are compared with the standard techniques with respect to the achievable terahertz pulse energy.
9
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Terahertz Emission from Narrow Gap Semiconductors Photoexcited by Femtosecond Laser Pulses

80%
Adomavičius R., Urbanowicz A., Molis G., Krotkus A.
Acta Physica Polonica A
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2005
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vol. 107
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issue 1
132-136
EN
Large increase in the emitted terahertz power was observed for p-InAs samples with the p-doping levels of approximately 10^{16}-10^{17} cm^{-3}. This increase was explained by a large surface depletion layer and an electric-field-induced optical rectification effect in the layer. Terahertz fields radiated by the samples of all three investigated Cd_xHg_{1-x}Te layers was of the same order of magnitude. No azimuthal angle dependence of the radiated signal was detected, which evidences that linear current surge effect is dominating over nonlinear optical rectification. Azimuthal angle and magnetic fields emission witness that it is caused by linear photo-Dember type processes.
10
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Theoretical Investigation of Large-Signal Noise in Nanometric Schottky-Barrier Diodes Operating in External Resonant Circuits

80%
Shiktorov P., Starikov E., Gružinskis V., Varani L., Vaissière J., Reggiani L., Pérez S., González T.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
396-399
EN
We report Monte Carlo simulations of electronic noise in heavily doped nanometric GaAs Schottky-barrier diodes operating in series with a parallel resonant circuit when a high-frequency large-signal voltage is applied to the whole system. Significant modifications of the noise spectrum with respect to the unloaded diode are found to occur in the THz-region.
11
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Monte Carlo Calculation of High Frequency Mobility and Diffusion Noise in Nitride-Based Semiconductors

80%
Starikov E., Shiktorov P., Gružinskis V., Varani L., Vaissière J., Palermo C., Reggiani L.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
408-411
FR
Monte Carlo simulations of high-field transport in semiconductor nitrides, GaN and InN, is used to calculate the velocity-field characteristics and the high-frequency behavior of the differential mobility, spectral density of velocity fluctuations, and noise temperature. It is found that due to very short relaxation time scales of nitrides, the characteristic frequencies associated with extrema and cutoff decay of the negative differential mobility, etc. are shifted to higher frequency range with respect to the case of standard A_3B_5 compounds. This property is favorable for applications of nitrides in the THz frequency range.
12
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Excitation of Deep Defects by Intense Terahertz Radiation

80%
Ganichev S.
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vol. 96
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issue 5
535-544
EN
An analysis is done of the ionization of deep impurity centers by high-intensity terahertz radiation, with photon energies tens of times lower than the impurity ionization energy. Under these conditions, ionization can be described as direct tunneling and phonon-assisted tunneling in which carrier emission is accompanied by defect tunneling in configuration space and electron tunneling in the electric field of the radiation. Within a broad range of intensity, frequency, and temperature, the terahertz electric field of the radiation acts like a static field. For very high frequencies and low temperatures an enhancement of tunneling as compared to static fields was observed. The transition between the quasi-static and the high frequency regime is determined by the tunneling time. For the case of deep impurities this is the time of redistribution of the defect vibrational system which depends strongly on temperature and the impurity structure.
13
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Terahertz Resonant Detection by Plasma Waves in Nanometric Transistors

80%
Teppe F., El Fatimy A., Boubanga S., Knap W., Seliuta D., Valusis G., Chenaud B.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
815-820
EN
The plasma waves in gated two-dimensional electron gas have a linear dispersion law, similar to the sound waves. The transistor channel is acting as a resonator cavity for the plasma waves, which can reach frequencies in the THz range for a sufficiently short gate length field effect transistors. A variety of possible applications of field effect transistor operating as a THz device were suggested. In particular, it was shown that the nonlinear properties of plasma oscillations can be utilized for THz tunable detectors. During the last few years THz detection related to plasma wave instabilities in nanometer size field effect transistors was demonstrated experimentally. In this work we review our recent experimental results on the resonant plasma wave detection at cryogenic and room temperatures.
14
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Coherent Terahertz Radiation Generation Assisted by Low-Temperature Optical Phonon Emission: Achievements and Perspectives

80%
Shiktorov P., Starikov E., Gružinskis V., Varani L., Reggiani L.
Acta Physica Polonica A
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2008
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vol. 113
|
issue 3
795-802
EN
The conditions for THz radiation generation caused by electron transite time resonance in momentum and real spaces under low-temperature optical-phonon emission are analyzed. It is shown that such a phenomenon provides a unique possibility to realize the sub-THz and THz radiation generation at the border of the electrooptical and electronic techniques by using both the approaches: (i) amplification of transverse electromagnetic waves in 3D bulk materials and 2D quantum wells, and (ii) longitudinal current instabilities in submicron and overmicron n⁺nn⁺ diodes.
15
Content available remote

Few-Cycle Laser Pulses: The Carrier-Envelope Phase, Its Role in the THz Emission from Laser-Generated Plasmas and a New Way to Measure It

80%
Kress M., Löffler T., Thomson M., Roskos H., Dörner R., Gimpel H., Zrost K., Ergler T., Moshammer R., Morgner U., Ullrich J.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
769-776
EN
Terahertz emission from laser-generated air plasmas has recently been identified as an interesting source for THz radiation. High intensities and a large bandwidth of the THz pulses can be achieved. We briefly review several mechanisms which were employed to generate the quasi-static dipole moment needed for the optical rectification process. This leads us to a discussion of a specific application of THz emission from an air plasma, namely the investigation of the carrier-envelope phase of few-cycle optical pulses. Such pulses of a duration of less than 10 fs induce a spatial charge asymmetry in the plasma directly via non-linear tunneling ionization. The asymmetry, and with it the emission of the THz radiation from the plasma, depend on the carrier-envelope phase, with the consequence that one can determine the phase by measurement of the amplitude and polarity of the THz pulse.
16
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THz Emission Induced by an Optical Beating in Nanometer-Length High-Electron-Mobility Transistors

80%
Nouvel P., Torres J., Marinchio H., Laurent T., Palermo C., Varani L., Teppe F., Shiktorov P., Starikov E., Gruzinskis V.
Acta Physica Polonica A
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2011
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vol. 119
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issue 2
199-202
EN
Experimental results of direct measurement of resonant terahertz emission optically excited in InGaAs HEMT channels are presented. The emission was attributed to two-dimensional plasma waves excited by photogeneration of electron-hole pairs in the HEMT channel at the frequency of the beating of two cw-laser sources. The presence of resonances for the radiation emission in the range of f_0 ± 10 GHz (with f_0 from 0.3 up to 0.5 THz) detected by a Si-bolometer is found. The intensity of THz emission exhibits a nonlinear growth with increase of the pumping power.
17
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Resistive Sensor for Short High-Power Microwave Pulse Measurement in Millimeter Wave Range

80%
Tamošiūnas V., Kancleris Ž., Dagys M., Simniškis R., Agee F.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
420-424
EN
We report on the numerical investigation of the resistive sensor for the 78-118 GHz range. A three-dimensional finite-difference time-domain method was applied to simulate the wave propagation within a waveguide segment with the semiconductor sensor attached to a wider wall of the wave-guide. The electric field distribution, voltage standing-wave ratio and the average electric field dependences on frequency have been determined for several sets of dimensions and specific resistances of the sample. It is demonstrated that a proper selection of the dimensions and specific resistance of the sample can compensate the waveguide dispersion and the decrease of the electron heating effect with frequency. Therefore, a nearly constant sensitivity of the sensor can be obtained for the entire frequency range.
18
Content available remote

Phonon-Plasmon Interactions in Inhomogeneous Semiconductor Plasma Embedded with Nanoparticle Cluster

80%
Ghosh S., Dubey P.
Acta Physica Polonica A
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2018
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vol. 133
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issue 5
1287-1293
EN
Phonon-plasmon interaction in inhomogeneous piezosemiconductor embedded with a nanoparticle cluster is examined using hydrodynamic model of plasma and macroscopic model of piezoelectric media. Present work dealt with the extensive investigation of acoustic wave amplification characteristics. The effects of density gradient δ and non-dimensional parameter l related to nanoparticle cluster on acoustic gain have been studied with varying medium electron density n_{0e}, wave frequency ω and velocity ratio ϑ_{0}/ϑ_{s}. The results so obtained, infer that the varying inhomogeneity and presence of nanoparticle cluster within the semiconductor plasma medium play decisive role in depicting the gain characteristics of acoustic wave.
19
Content available remote

Generation of Terahertz Radiation by Large-Aperture Photoconductive Antennas in Condition of a High Level Excitation

80%
Trukhin V., Buyskikh A.
Acta Physica Polonica A
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2011
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vol. 119
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issue 2
206-209
EN
Theoretical and experimental results about generation coherent terahertz (THz) radiation in photoconductive medium in condition of a high level excitation are presented. Employing self-consistent analytical approach to the set of non-equilibrium Boltzmann equation for charge carriers and Maxwell equations for electromagnetic radiation we have studied the radiation phenomena in non-equilibrium e-h plasma excited in the photoconductive gap of terahertz radiating large-aperture photoconductive antenna by an ultrashort laser pulse. Equally with the effect of the radiation screening, the effect of the non-linear absorption of an optical pump pulse (bleaching of photoconductive medium) was taken into account. It was shown that the effect of nonlinear absorption reconstructs the dynamics of the generation of terahertz radiation and must take into account the effects associated with the spread of the generated wave and the wave of excitation.
20
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Studies of Response of Metal - Porous Silicon Structures to Microwave Radiation

80%
Stupakova J., Ašmontas S., Gradauskas J., Zagadskij V., Shatkovskis E., Sužiedėlis A.
Acta Physica Polonica A
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2006
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vol. 110
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issue 6
817-822
EN
Structures containing layers of porous silicon with two metal contacts are investigated. Porous silicon is manufactured by anodizing p-type crystalline silicon plates of resistivity of 0.4 Ω cm. Contacts for the samples are made by additional boron doping of the surface and by thermal evaporation of aluminium. Resistance and current-voltage characteristics are investigated. Response of the porous silicon layer containing structures under action of pulsed microwave radiation was investigated for the first time. The origin of the response is discussed.
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