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  1. 52 Acta Physica Polonica A

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  1. 12 Shiktorov P.

  2. 12 Starikov E.

  3. 11 Gružinskis V.

  4. 8 Varani L.

  5. 6 Łusakowski J.

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1
Content available remote

Hot-Electron Effects in High-Resistivity InSb

100%
Ašmontas S., Subačius L., Valušis G.
Acta Physica Polonica A
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1993
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vol. 84
|
issue 4
717-720
EN
We report that in the presence of random potential of the conduction band hot-electron transport can exhibit some novel features, some of which can be observed in dependencies of electric conductivity, mean electron energy and noise temperature on electric field strength.
2
Content available remote

Electron Temperature in Semi-Insulating GaAs for Low Electric Fields

100%
Zduniak A., Łusakowski J., Nowak G.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
777-780
EN
Heating of electrons by electric fields smaller than that required for generation of domain oscillations was investigated in samples of EL2-rich semi-insulating GaAs. Current-voltage characteristics were measured as a function of temperature between 268 K and 330 K. They exhibit a sublinear shape which is interpreted as a result of an enhanced electron capture on the EL2. The capture rate and the electron temperature as a function of the electric field was determined. A fitting procedure gave the value of electron capture cross-section on the EL2 to be 2.7 × 10^{-13} cm^{2} which agrees with literature data.
3
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Nonlinear Coupling of Oscillatory Modes in Current Flow in Semi-Insulating GaAs

100%
Karpińska K., Łusakowski J.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
425-428
EN
Spontaneous current oscillations in semi-insulating (SI) GaAs sample caused by high electric field domains nucleation were perturbed by modulated illumination. Coupling between domain and photocurrent oscillations leads to quasiperiodic and frequency-locked behaviour. The observed Arnol'd tongues structure follows the Farey tree ordering and agrees with predictions of the circle map theory. We also suggest a possible mechanism responsible for the coupling of the modes.
4
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Electron-Electron Scattering Influence on Hot Electron Transport in Semiconductors

100%
Dedulewicz S., Kancleris Ž.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
353-356
EN
Electron-electron scattering has been shown to manifest itself when scattering by optical phonons is of importance. The strongest influence has been observed in the slightly heated electron system at the lattice temperature T ≈ T_{0}/5 (T_{0} being the characteristic temperature of optical phonon).
5
Content available remote

Spatiotemporal Transport Processes in Semiconductor Gas Discharge Structure with GaAs Photodetector

63%
Yűcel Kurt H., Salamov B.
Acta Physica Polonica A
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2008
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vol. 114
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issue 4
819-834
EN
In a semiconductor gas discharge structure with diameters much larger than an inter-electrode distance, the effects of different parameters (i.e. electrode separation, gas pressure, diameter of the GaAs photodetector, etc.) on electrical breakdown and current oscillations were studied. Non-stationary and non-homogeneous states are generated in the structure, through the spatially uniform irradiation of the semiconductor photodetector. Instabilities occur due to the nonlinear features of the semiconductor photocathode, while the gas discharge serves to visualize transport processes in GaAs. Spatiotemporal variations of current and discharge light emissions are studied with the above-mentioned control parameters. Transformation of the profile and amplitude of the current densities of the filaments in different regions of the current-voltage characteristic are widely studied. Instabilities of spatially non-uniform distributions resulting in the formation of multiple current filaments with increasing voltages above the critical values are observed. A semiconductor gas discharge structure with an N-shaped current-voltage characteristic is analyzed via both the current and discharge light emissions data which shows the electrical instability in the GaAs photodetector.
6
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Small-Signal Characterization of FET/HEMT for Terahertz Applications

63%
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.
7
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Monte Carlo Simulation of Noise and THz Generation in InP FET at Excess of Electrons in Channel

63%
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.
8
Content available remote

Modeling of THz-Electro-Optical Sampling Measurements

63%
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.
9
Content available remote

Corner Dissipation in Quantum Hall Systems

63%
Riess J., Magyar P.
Acta Physica Polonica A
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1993
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vol. 84
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issue 3
523-526
EN
A description of the onset of dissipation in the integer quantum Hall effect is given, where the electric field across the sample is expressed through a time dependent vector potential. This brings the essentially time dependent, non-stationary nature of the problem into focus. The electric field induces transitions between the levels of the disorder broadened Landau band. Above a critical electric field the particles are driven upwards in energy space beyond the Fermi level, which leads to dissipation since the accumulated energy is lost to the heat bath after τ_{in}, the time between two inelastic events. Thus the dissipated power is obtained without the use of the traditional (linear response) transport formulae. As an application we investigate the dissipation in the corner region of a Hall bar. The results are in reasonable accordance with recent experiments exploiting the fountain pressure effect.
10
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Conductivity of Optically Excited Electrons in GaAs in Quantizing Magnetic Fields

63%
Łusakowski J., Grynberg M., Huant S.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
482-486
EN
Magnetoconductivity (σ) measurements on an n-type molecular beam epitaxy grown epitaxial layer and on a bulk liquid encapsulated Czochralski grown undoped semi-insulating GaAs samples were performed for magnetic fields (B) up to 21 T at 4.2 K. To enable current measurements in a wide range of B both samples were permanently illuminated with a band-to-band light. It is shown that for sufficiently high magnetic fields σ(B) dependence is the same for both materials. This result underlines a role of scattering by long-range fluctuations of the electrostatic potential in high-quality n-GaAs in quantizing magnetic fields.
11
Content available remote

Influence of Impact Ionization of Shallow Donors on Luminescence in GaAs

63%
Wysmołek A., Łusakowski J.
Acta Physica Polonica A
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1995
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vol. 87
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issue 1
261-264
EN
Luminescence spectra of n-type molecular beam epitaxial layer and semi-insulating liquid encapsulated Czochralski grown bulk GaAs were mea­sured at liquid helium temperature for zero electric field and for fields which caused impact ionization of shallow donors. Application of the electric field caused a decrease in the luminescence intensity and a broadening of all ob­served structures. It was found that the electric field changed the lumines­cence spectrum of the n-type material in a different way than it did in the case of the semi-insulating one. For the n-type sample, an intensity of exci­tonic lines decreased much more than that of donor-acceptor lines when the electric field grew. A contrary was observed for the semi-insulating sample. An explanation of the result is proposed which takes into account an in­fluence of ionised impurity scattering and localization in fluctuations of the electrostatic potential on the luminescence process.
12
Publication available in full text mode
Content available

Hot Phonons in a Biased Two-Dimensional InGaAs Channel

63%
Aninkevičius V., Liberis J., Matulionis A., Matulionienė I.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
304-309
EN
Experimental dependence of microwave noise temperature on supplied electric power is used to estimate hot-phonon number in a modulation-doped In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}As/In_{0.7} Ga_{0.3}As/In_{0.52}Al_{0.48}As two-dimensional electron gas channel (n_{2D}=2.3×10^{12} cm^{-2}). The nonequilibrium occupancy of the involved longitudinal optical phonon states exceeds the equilibrium one nearly twice at 2 kV/cm electric field.
13
Publication available in full text mode
Content available

High-Speed Quadratic Electrooptic Nonlinearity in dc-Biased InP

63%
Subačius L., Kašalynas I., Vingelis M., Aleksiejūnas R., Jarašiūnas K.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
280-285
EN
We present experimental data on degenerate four-wave mixing as well as simulation results of fast optical nonlinearities in highly-excited semi-insulating InP under applied dc-field. Hot-electron transport governed enhancement of optical nonlinearity is obtained by applying a dc-field of 10-14 kV/cm at full-modulation depth of a light-interference pattern. The hydrodynamic model, which incorporates both free-carrier and photorefractive nonlinearities is used to explain the experimentally observed features. We show that the enhancement of optical nonlinearity is due to the quadratic electrooptic effect.
14
Publication available in full text mode
Content available

Optically Driven Domain Instability and High-Frequency Current Oscillations in Photoexcited GaAs under Nonuniform Electron Heating

63%
Subačius L., Kašalynas I.
Acta Physica Polonica A
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2005
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vol. 107
|
issue 2
275-279
EN
Fast domain instabilities induced by light-interference pattern in dc-biased semi-insulating GaAs are investigated. Current oscillations in GHz-frequency range are observed due to nonuniform electron heating and domains formation in light-induced grating. Characteristic features of the oscillations under various experimental conditions are presented. Numerical calculations based on the hot-electron hydrodynamic model are used to explain the observed nonlinear features under various external bias and periods of the grating.
15
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Non-Activated Conductivity of Hot Electrons in Localization Regime

63%
Łuskowski J., Grynberg M.
Acta Physica Polonica A
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1995
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vol. 87
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issue 1
253-256
EN
Temperature (T) dependence of conductivity (σ) was studied in semi­-insulating GaAs as a function of the magnetic field (B) for 1.8 K < T < 40 K for high electric fields. An infrared illumination of a sample and application of an electric field caused a non-equilibrium distribution of electrons in the conduction band. An increase in B caused a localization transition which manifested itself by a gradual disappearance of the impact ionization of shallow bound states. The transition was connected with a change from a non-activated to an activated conductivity only if T > 4 K, otherwise σ showed only a non-activated character. It is proposed that for T < 4 K the electron distribution function is mostly determined by optical and electric field excitations, which results in a non-activated conductivity. For T > 4 K thermal excitations become dominant which leads to an activated character of σ.
16
Publication available in full text mode
Content available

Small and Large Signal Analysis of Terahertz Generation from InN n^+nn^+ Structures with Free-Carrier Grating

63%
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.
17
Content available remote

Fractal Dimensions from Chaotic Oscillations in Semi-Insulating GaAs

63%
Zduniak A., Łusakowski J.
Acta Physica Polonica A
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1993
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vol. 84
|
issue 3
575-578
EN
Relaxation and domain current oscillations in undoped semi-insulating GaAs were observed at room temperature for a broad range of voltage applied to a sample. The oscillations were characterized by a reconstruction of an attractor of the system. An analysis of the attractor helped to discriminate between the two likes of oscillations. A transition from one like of oscillations to the other was connected with a chaotization of the current. A chaotic state of the system was analyzed by calculations of fractal dimensions D_{q} for -0.6 < g < 40 and the f(α) function.
18
Content available remote

Third-Order Susceptibility of Silicon Crystals Measured with Millimeter-Wave Gyrotron

63%
Narkowicz R., Siegrist M., Moreau P., Hogge J., Raguotis R., Brazis R.
Acta Physica Polonica A
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2011
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vol. 119
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issue 4
509-513
EN
We investigate experimental dependence of the third harmonic generation efficiency in the n-type Si crystals on the geometrical dimensions of the sample, polarization and power of the fundamental wave. The efficiency increases monotonically with the rise of the sample thickness up to a threshold value, and decreases dramatically above the threshold. At shorter propagation distances the generation efficiency could be correctly simulated using the layered medium approximation and the numerically calculated electron drift velocity response to the pumping wave electric field to describe the change of the semiconductor properties under high-power microwave irradiation.
19
Publication available in full text mode
Content available

High-Frequency Noise Sources in Quantum Wells

51%
Ardaravičius L., Liberis J., Matulionis A.
Acta Physica Polonica A
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2002
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vol. 102
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issue 2
329-335
EN
Hot-electron noise is investigated for InGaAs and InAs quantum wells containing a two-dimensional electron gas channel in a pulsed electric field applied parallel to the interfaces. Noise sources resulting from hot-electron "thermal" motion, electron temperature fluctuations, and real-space transfer are observed. The experimental results on hot-electron "thermal" noise are used to estimate energy relaxation time in the field range where other sources do not play any important role. Measurements of noise anisotropy in the plane of electron confinement are used to discuss real-space-transfer noise. High-frequency noise technique is used to study hot-electron trapping, and trap location in InAlAs/InGaAs/InAlAs heterostructure channels is determined.
20
Publication available in full text mode
Content available

Theoretical Investigation of Large-Signal Noise in Nanometric Schottky-Barrier Diodes Operating in External Resonant Circuits

51%
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.
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