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1
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Energy Levels and Electrical Activity of Dislocation Electron States in GaAs

100%
Wosiński T., Figielski T.
Acta Physica Polonica A
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1993
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vol. 83
|
issue 1
51-58
EN
Experimental results are presented confirming that the two energy levels in GaAs: E_{c} - 0.68 eV and E_{v} + 0.37 eV, discovered in plastically deformed crystals, belong actually to dislocations. In view of recent identification of the electron state of misfit dislocations at an InGaAs/GaAs interface, a correspondence between these levels and dislocation types has been reinterpreted. The first mentioned leve1 belongs likely to α while the second one to β dislocations of 60° (glide set) type. Such a correspondence is compatible with the observed effect of irradiation on dislocation glide motion in GaAs. It is also argued that these energy levels are involved in the phenomenon of unquenchability of the EL2 defects placed in high-stress regions near dislocations.
2
Content available remote

On Electrostatic Aharonov-Bohm Effect in Solids

81%
Figielski T., Wosiński T., Morawski A., Mąkosa A.
Acta Physica Polonica A
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1998
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vol. 94
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issue 2
305-308
EN
We analyse conditions for an appearance of the electrostatic Aharonov- Bohm interference in two systems: a single-channel quantum-wire loop and an open ballistic quantum dot. We show that in the first system the effect will be destroyed by charge fluctuations, which probably is the reason why it has not been clearly observed, while in the second system the effect is still open for exploration.
3
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Electric Field Enhanced Emission of Holes from the Double Donor Level of the EL2 Defect in GaAs

81%
Mąkosa A., Wosiński T., Szkiełko W.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
813-816
EN
Strong electric-field enhancement of the thermal emission rate of holes from the doubly ionized charge state of the EL2 defect was revealed with the deep-level transient spectroscopy in p-type GaAs and analyzed in a model of phonon-assisted tunnel effect. Similar dependence observed for the electric field directions parallel to three main crystallographic axes suggests tetrahedral symmetry of the defect which is consistent with its identification as the arsenic antisite.
4
Content available remote

Deep-Level Defects at Lattice-Mismatched GaAsSb/GaAs Interface

81%
Wosiński T., Mąkosa A., Raczyńska J.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
369-372
EN
Lattice-mismatch-induced defects were studied by means of deep-level transient spectroscopy in high-purity GaAs_{1-x}Sb_{x} layers (x = O to 3%) grown by liquid phase epitaxy on GaAs substrates. Microscopic nature and formation mechanism of two electron traps and two hole traps, which ap­peared in the layers as a result of Sb incorporation into the crystal lattice, are briefly discussed.
5
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Native Defects in Gallium Arsenide Grown by Synthesis, Solute Diffusion Method

81%
Fronc K., Mąkosa A., Wosiński T.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
349-352
EN
High-purity n-type GaAs crystal was grown by the Synthesis, Solute Diffusion (SSD) method. Deep Level Transient Spectroscopy (DLTS) characterization of the crystal revealed three deep traps related to native defects. Microscopic origin of the traps is discussed and prospective use of SSD-grown GaAs as a bulk material with the high luminescence efficiency is emphasized.
6
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Transformation of Native Defects in GaAs under Ultrasonic Treatment

81%
Mąkosa A., Wosiński T., Witczak Z.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
653-656
EN
Effect of high-intensity ultrasonic vibration on the spectrum of deep electron traps in bulk GaAs has been studied giving rise to a discussion on microscopic structure of native defects associated with the traps.
7
Content available remote

Effect of Interface Roughness on Resonant Tunnelling in Double-Barrier Heterostructures

81%
Figielski T., Wosiński T., Mąkosa A.
Acta Physica Polonica A
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1996
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vol. 90
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issue 4
777-780
EN
We argue that the well-boundary roughness in a double-barrier heterostructure induces subsidiary subbands in the quantum well which, in turn, lead to the appearance of a broad shoulder beyond the principal resonance peak in the current-voltage characteristics.
8
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Observation of the Coulomb Blockade at 77 K in a Lattice-Mismatched GaAs/Si Heterojunction

81%
Figielski T., Wosiński T., Mąkosa A., Riesz F.
Acta Physica Polonica A
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1997
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vol. 92
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issue 4
745-748
EN
We investigated current-voltage characteristics of a lattice-mismatched GaAs(n)/Si(p) heterojunction. For low bias voltages at 77 K it exhibits a behaviour characteristic of the Coulomb blockade. We discuss why this unexpected phenomenon can occur in the investigated structures.
9
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Inelastic Electron Scattering in Double-Barrier Resonant Tunneling Structure Revealed with Photoexcitation

71%
Figielski T., Mąkosa A., Wosiński T., Harness P., Singer K.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
817-819
EN
We investigated current-voltage and photocurrent-voltage characteristics of a double-barrier resonant tunneling structure based on AlGaAs. To explain the observed "double-step" feature of the characteristics, we have proposed a mechanism including a multiple phonon emission of an electron dwelling in the quantum well.
10
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Resonant Tunnelling in Double-Barrier Heterostructures with an Accumulation Layer

71%
Wosiński T., Figielski T., Mąkosa A., Wrotek S., Dobrowolski W.
Acta Physica Polonica A
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1998
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vol. 94
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issue 3
617-621
EN
Two modes of electron gas injection in resonant tunnelling through GaAs/AlGaAs double-barrier heterostructures were revealed while studying their current-voltage characteristics. Examining peculiarities of the characteristics within the temperature range 4-350 K and under a high magnetic field, we were able to distinguish the contribution to resonant tunnelling of ballistic electrons injected from a three-dimensional electron gas in the emitter contact and that of electrons injected from a two-dimensional electron gas in the accumulation layer formed near the emitter barrier.
11
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Three- versus Two-Dimensional Electron Gas Injection in Resonant Tunnelling

71%
Figielski T., Wosiński T., Mąkοsa A., Kaniewska M., Regiński K.
Acta Physica Polonica A
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1995
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vol. 88
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issue 4
707-710
EN
A small "precursor" of resonance is observed before the main resonance peak in the current-voltage characteristic of double-barrier resonant-tunnel­ling devices. The competition between the precursor and main-peak current is examined within the temperature range 4.2-400 K. The precursor is interpreted as 3DEG contribution to the resonant tunnelling dominated by a 2DEG injection from a triangular well formed under bias in the emitter spacer layer.
12
Content available remote

Aharonov-Bohm Effect at Misfit Dislocations in GaAsSb/GaAs Heterostructures

71%
Figielski T., Wosiński T., Mąkosa A., Dobrowolski W., Raczyńska J.
Acta Physica Polonica A
|
1996
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vol. 90
|
issue 4
773-776
EN
We examined the current flowing through p^{+}-n junction of the lattice mismatched GaAs_{1-x}Sb_{x}/GaAs heterostructure in a transverse magnetic field at 1.8 K. We have found the appearance of current oscillations, periodic as a function of the magnetic field, that are due to the Aharonov-Bohm effect of holes passed around charged dislocations.
13
Content available remote

Deep-Level Defects in MBE-Grown GaN-Based Laser Structure

62%
Tsarova T., Wosiński T., Mąkosa A., Skierbiszewski C., Grzegory I., Perlin P.
Acta Physica Polonica A
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2007
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vol. 112
|
issue 2
331-337
EN
We present results of deep-level transient spectroscopy investigations of defects in a GaN-based heterostructure of a blue-violet laser diode, grown by plasma-assisted molecular beam epitaxy on a bulk GaN substrate. Three majority-carrier traps, T1 at E_C - 0.28 eV, T2 at E_C - 0.60 eV, and T3 at E_V + 0.33 eV, were revealed in deep-level transient spectra measured under reverse-bias conditions. On the other hand, deep-level transient spectroscopy measurements performed under injection conditions, revealed one minority-carrier trap, T4, with the activation energy of 0.20 eV. The three majority-carrier traps were revealed in the spectra measured under different reverse-bias conditions, suggesting that they are present in various parts of the laser-diode heterostructure. In addition, these traps represent different charge-carrier capture behaviours. The T1 trap, which exhibits logarithmic capture kinetics, is tentatively attributed to electron states of dislocations in the n-type wave-guiding layer of the structure. In contrast, the T2, T3, and T4 traps display exponential capture kinetics and are assigned to point defects.
14
Content available remote

Native Deep-Level Defects in MBE-Grown p-Type CdTe

62%
Olender K., Wosiński T., Mąkosa A., Dłużewski P., Kolkovsky V., Karczewski G.
Acta Physica Polonica A
|
2011
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vol. 120
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issue 5
946-949
EN
Deep-level transient spectroscopy was used to study the defect levels in p-type CdTe layers grown by the molecular-beam epitaxy technique on lattice-mismatched GaAs substrates. In our measurements we have observed five hole traps. Two of the traps, displaying exponential capture kinetics, have been assigned to native point defects, the Cd vacancy and a complex formed of Cd vacancy and Te antisite, produced in the CdTe layers during their growth. The other two traps have been attributed to electronic states of threading dislocations on the ground of their logarithmic capture kinetics. The last trap, which was observed only when the investigated space charge region was close to the metal-semiconductor interface, has been ascribed to surface states.
15
Content available remote

Fine Structure of Resonant-Tunneling Peak in GaAs/AlAs Double-Barrier Heterostructure

62%
Vitusevich S., Figielski T., Mąkosa A., Wosiński T., Belyaev A., Konakova R., Kravchenko L.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
377-380
EN
For the first time we observed a fine oscillatory structure, with the period of 36 mV, of the resonant tunneling peak in the current-voltage char­acteristic of a double-barrier heterostructure. We attribute it to a sequential single-phonon emission of ballistic electrons which tunneled out from the quantum well through the collector barrier.
16
Content available remote

Magnetically Controlled Interference of Ballistic Electrons Tunnelled throughout the Double-Barrier Resonator

62%
Figielski T., Wosiński T., Mąkosa A., Dobrowolski W., Vitusevich S., Belyaev A.
Acta Physica Polonica A
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1996
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vol. 90
|
issue 4
781-784
EN
An effect of magnetic field normal to the tunnel current on the amplitude and phase of the fine oscillatory structure, discovered in the resonance current-voltage curve in double-barrier AlAs/GaAs heterostructures, has been examined. All the obtained results are consistently explained in terms of the interference of ballistic electrons, escaped from the quantum well, in the collector part of the structure.
17
Content available remote

Bistability of (Ga,Mn)As Ferromagnetic Nanostructures Due to the Domain Walls Switching

62%
Andrearczyk T., Wosiński T., Mąkosa A., Figielski T., Wróbel J., Sadowski J.
Acta Physica Polonica A
|
2009
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vol. 116
|
issue 5
901-903
EN
We designed and investigated four-arm nanostructures, composed of two perpendicularly crossed stripes, fabricated from ferromagnetic (Ga,Mn)As layer by means of electron-beam lithography patterning and chemical etching. The nanostructures exhibit a bistable resistance behavior resulting from two configurations of magnetic domain walls in the central part of the structures. We demonstrate a possibility of switching between two stable resistance states in zero magnetic field by applying a pulse of either weak magnetic field or electric current through the structure.
18
Content available remote

Planar Hall Effect in Ferromagnetic (Ga,Mn)As/GaAs Superlattices

62%
Wesela W., Wosiński T., Mąkosa A., Figielski T., Sadowski J., Terki F., Charar S.
Acta Physica Polonica A
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2007
|
vol. 112
|
issue 2
369-373
EN
The planar Hall effect was used for investigation of magnetic anisotropy in short period (Ga,Mn)As/GaAs superlattices epitaxially grown on (001) oriented GaAs substrate. The results confirmed the existence of low-temperature magnetocrystalline anisotropy in the superlattices with the easy magnetic axes directed along the two in-plane 〈100〉 directions. Attention is paid to the two-state behaviour of the planar Hall resistance at zero magnetic field that provides its usefulness for applications in non-volatile memory devices.
19
Content available remote

Magneto-Transport Characterization of Four-Arm Nanostructure Based on Ferromagnetic (Ga,Mn)As

52%
Andrearczyk T., Wosiński T., Figielski T., Mąkosa A., Tkaczyk Z., Łusakowska E., Wróbel J., Sadowski J.
Acta Physica Polonica A
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2008
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vol. 114
|
issue 5
1049-1054
EN
We report on results of magneto-transport measurements performed on four-arm nanostructure fabricated from p-type ferromagnetic Ga_{0.92}Mn_{0.08}As layer. The results reveal hysteresis-like behaviors of low field magnetoresistance. We interpret the magnetoresistance in terms of domain walls, which are expected to be trapped inside the nanostructure at some particular positions and which contribute to the total resistance.
20
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Content available

Magnetotransport through Nanoconstriction in Ferromagnetic Semiconductor (Ga,Mn)As

52%
Figielski T., Wosiński T., Pelya O., Sadowski J., Morawski A., Mąkosa A., Dobrowolski W., Jagielski J., Wróbel J.
Acta Physica Polonica A
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2003
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vol. 103
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issue 6
525-531
EN
We studied narrow (submicron) constrictions in the layers of ferromagnetic semiconductor (Ga,Mn)As. We have demonstrated a contribution of the quantum localization effects to the magnetoresistance of the constricted samples. We have also found a negative contribution of a domain wall trapped in the constriction to the resistance, due presumably to the erasing of the localization effects by the domain wall.
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