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1
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Current Shot Noise and Bunching of Electrons in Multilevel Quantum Dots

100%
Michałek G., Bułka B.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
27-30
EN
Currents and their fluctuations in multilevel quantum dots are studied theoretically in the limit of sequential tunneling. The spin degrees of freedom, many-body electronic states (singlet and triplet) as well as relaxation processes between the levels of the quantum dots are considered. In general, due to the rapid relaxation processes the shot noise is sub-Poissonian, however for a large polarization of the outgoing currents from the singlet and triplet states one gets the super-Poissonian type of the shot noise due to the bunching of tunneling events.
2
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High-Frequency Noise Sources in Quantum Wells

80%
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.
3
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Microplasma Noise Stimulated by Microwave Electric Field

80%
Namajūnas A., Tamaševičius A., Mykolaitis G., Bumelienė S., Požela J.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
369-372
EN
Si and GaAs avalanche diodes containing microplasmas are investigated. Microwave field applied to the diode in addition to reverse dc bias results in considerable spread of noise spectrum and in the increase of noise power. The microplasma noise spectra cover very high (30 to 300 MHz) and ultrahigh (300 to 1000 MHz) frequency bands, while the effective noise temperature is about 10^8 K.
4
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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.
5
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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.
6
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Hot Carrier Effects in Optically Detected Cyclotron Resonance Studies of III-V Semiconductors

80%
Karpińska K., Dedulewicz S., Godlewski M.
Acta Physica Polonica A
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1992
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vol. 82
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issue 4
623-626
EN
The mechanisms of irregular photoluminescence intensity oscillations, as observed in optically detected cyclotron resonance experiments, are discussed. Two possible scenarios are analyzed, both requiring impact ionization of the center(s) by electric field accelerated free carriers. The first assumes coexistence of dielectric and energy relaxation processes. The second assumes a subsequent impact ionization of two different centers.
7
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Signature of Hot Phonons in Reliability of Nitride Transistors and Signal Delay

80%
Matulionis A., Liberis J., Matulionienė I., Šermukšnis E., Leach J., Wu M., Ni X., Morkoç H.
Acta Physica Polonica A
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2011
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vol. 119
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issue 2
225-227
EN
Lifetime of non-equilibrium (hot) phonons in biased GaN heterostructures with two-dimensional electron gas channels was estimated from hot-electron fluctuations. Dependence of the lifetime on the electron density is not monotonous - the resonance-type fastest decay serves as a signature of hot phonons. The signature is resolved in nitride heterostructure field effect transistors when the gate voltage is used to change the channel electron density. The transistor cut-off frequency decreases on both sides of the resonance in agreement with the enhanced electron scattering caused by longer hot-phonon lifetimes. The signature is also noted in device reliability experiment: the enhanced temperature of hot phonons, possibly, triggers formation of new defects and accelerates device degradation.
8
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Statistics of Tunneling Events in Three-Terminal Hybrid Devices with Quantum Dot

80%
Michałek G., Bułka B., Domański T., Wysokiński K.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
391-393
EN
We investigate statistics of the tunneling events in the short time limit in terms of the waiting time distribution (WTD), defined as the probability for a delay time between two subsequent transitions of particles, and consider it for a quantum dot (QD) strongly coupled to a superconducting and weakly coupled to two normal electrodes. Our study focuses on the WTD in the subgap transport, when coherent exchange of the Cooper pairs occurs between the QD and the superconductor. The dynamics can be described in terms of a Markovian generalized master equation for the reduced density matrix. We observe coherent oscillations between the Andreev bound states in the correlated jumps, both for the local and non-local WTDs. In addition the analysis of the transient currents give us some insight into dominant relaxation processes in short time scales.
9
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Strong Reduction of 1/f Noise by Carbon Doping in Epitaxial Fe/MgO(100) 12~ML/Fe Magnetic Tunnel Junctions with Barrier Defects

80%
Herranz D., Guerrero R., Cascales J., Aliev F., Hehn M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 5-6
981-984
EN
We report on the strong influence of carbon doping on 1/f noise in fully epitaxial Fe/MgO(100) 12 ML/Fe magnetic tunnel junctions in comparison with undoped junctions with a large density of barrier defects. Carbon influences the relaxation of defects, the reconstruction of the interface and the symmetry transformation of interface resonance states, which are suggested to contribute to the strong reduction of the 1/f noise. Our study demonstrates that doping with light elements could be a versatile tool to improve the electron transport and noise in epitaxial magnetic tunnel junctions with a large density of barrier defects.
10
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High-Frequency Noise in Modern FET/HEMT Channels Caused by the Excitation of 2D-Plasma Waves

80%
Shiktorov P., Starikov E., Gružinskis V., Varani L., Reggiani L.
Acta Physica Polonica A
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2011
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vol. 119
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issue 2
117-120
EN
The problems related with the intrinsic noise in FET/HEMT channels induced by continuous branching of the total current between channel and gate are considered in the framework of a simple analytical model and its predictions on the current-noise spectra. Main branching-induced effects such as the appearance of an additional noise related to the excitation of plasma waves, its dependence on FET/HEMT embedding circuits, interference properties, etc. are analysed.
11
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Noise Enhancement due to Telegraphic Switching in a Two-Level Quantum Dot Coupled to Spin-Polarized Leads

80%
Ptaszyński K.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
526-528
EN
Current fluctuations in a two-level quantum dot coupled to the spin-polarized leads are studied by means of the Markovian master equation. It is shown, that transitions between spin configurations of the system cause switching between different current channels, which generates the super-Poissonian noise enhancement and the correlation between subsequent waiting times separating the successive tunneling events.
12
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Analysis of Conditions for Free-Carrier Grating Formation in InP n⁺nn⁺ Structures using Monte Carlo Technique

80%
Gružinskis V., Shiktorov P., Starikov E.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
943-946
EN
Electron transport in 5μm long InP n⁺nn⁺ structure with the n-region doping of 10^{15} cm^{-3} is theoretically investigated by the Monte Carlo particle technique at low lattice temperature (T = 10 K), when dominating scattering mechanism is the optical phonon emission. It is shown that at the constant bias a free-carrier grating can be formed inside the n-region. The free-carrier grating formation conditions are analysed by Monte Carlo particle simulation of electric field profiles and noise in the considered InP structure.
13
Content available remote

Plasma Instability Noise in InP n⁺nn⁺ Structures: Monte Carlo Simulation

80%
Gružinskis V., Shiktorov P., Starikov E.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
947-950
EN
The current noise in n⁺nn⁺ InP structures at dominating low temperature (T = 10 K) optical phonon emission is simulated by Monte Carlo particle technique. The n-region length of simulated structures is varied from 1 to 100 μm. The peaks related to the near collisionless and optical phonon emission dominated plasma instabilities are recognized in current noise spectral density spectra.
14
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Content available

Frequency Dependence of Shot Noise in Resonant Diodes under Coherent Tunneling

80%
Aleshkin V., Reggiani L., Rosini M.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
298-303
EN
The current spectral density and the Fano factor of a resonant diode are investigated as a function of frequency up to values just below the inverse of the transit time. We consider the case of coherent tunneling for a symmetric double barrier structure at voltages up to the first current peak at 77 K. At high frequencies the Fano factor is found to become suppressed systematically at a value of 0.25 independently of frequency. This suppression below 0.5 is an indication of coherent against sequential tunneling transport.
15
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Impact Ionization Driven Chaotic Photoluminescence Oscillations in Ga_{0.47}In_{0.53}As

80%
Godlewski M., Fronc K., Gajewska M., Chen W., Monemar B.
Acta Physica Polonica A
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1991
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vol. 80
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issue 2
271-274
EN
A new application of the Optically Detected Cyclotron Resonance (ODCR) is presented. We report impact ionization studies of bound exciton: (BE) and shallow donor related recombination processes in Ga_{0.47}In_{0.53}As. An appearance of chaotic oscillations in photoluminescence (PL) intensity is observed under condition of impact ionization of deeper donors.
16
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Waiting Time Correlations in Transport through Two Coupled Quantum Dots

80%
Ptaszyński K.
|
EN
Waiting times between subsequent tunneling events in the double quantum dot system are shown to be correlated. The magnitude and the sign of the cross-correlation depend on the degree and the character of modulation of tunneling rates in the one dot due to the interaction with the charge state of the other, as well as on the relation between different time scales of the system dynamics.
17
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Hot-Electron Transport and Microwave Noise in 4H-SiC

80%
Ardaravičius L., Liberis J., Kiprijanovič O., Matulionienė I., Matulionis A.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
310-314
EN
Hot-electron transport and microwave noise are investigated for n-type 4H-SiC (n=2×10^{17} cm^{-3}) subjected to a pulsed electric field applied parallel to the basal plane. At room temperature, the negative differential conductance, masked by field ionization at the highest fields, is observed in the field range between 280 and 350 kV/cm. The threshold fields for the negative differential conductance and field ionization increase with lattice temperature. The results on microwave noise are used to evaluate the effective hot-electron temperature and the hot-electron energy relaxation time.
18
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Optical and Electrical Noise Characteristics of Side Emitting LEDs

80%
Šaulys B., Kornijčuk V., Matukas J., Palenskis V., Pralgauskaitė S., Glemža K.
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EN
Low frequency noise characteristics of nitride based blue side emitting diodes have been investigated. It is shown that investigated devices distinguish by 1/f^α-type optical and electrical fluctuations caused by various generation-recombination processes through defects formed generation-recombination centers. At higher frequencies optical shot noise due to random photon emission prevails 1/f^α-type spectrum. The results have shown that low frequency optical and electrical noises are strongly correlated at small current region, but at higher forward current not correlated noise components dominate. Lenses and secondary optics of the investigated devices do not influence output light.
19
Content available remote

Hot-Electron Transport Noise and Power Dissipation in GaN Channels at High Density of Electrons

80%
Matulionis A., Liberis J., Matulionienė I., Ramonas M.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
967-970
EN
The experimental results on transport, noise, and dissipation of electric power for voltage-biased Si-doped GaN channels are compared with those of Monte Carlo simulation. The measured dissipated power shows a stronger hot-phonon effect than the simulated one. On the other hand, the experimental results on the electron drift velocity at high electric fields show a weaker hot-phonon effect as compared with the simulated one. The misfit can be reduced if a conversion of the friction-active nonequilibrium longitudinal optical phonons into the friction-passive longitudinal optical phonons is considered.
20
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External Noise Effects on the Electron Velocity Fluctuations in Semiconductors

80%
Persano Adorno D., Pizzolato N., Spagnolo B.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
985-988
EN
We investigate the modification of the intrinsic carrier noise spectral density induced in low-doped semiconductor materials by an external correlated noise source added to the driving high-frequency periodic electric field. A Monte Carlo approach is adopted to numerically solve the transport equation by considering all the possible scattering phenomena of the hot electrons in the medium. We show that the noise spectra are strongly affected by the intensity and the correlation time of the external random electric field. Moreover, this random field can cause a suppression of the total noise power.
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