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1
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High Resistivity AlGaAs Grown by Low Temperature MBE

100%
Radomska D., Ratajczak J., Regiński K., Bugajski M.
Acta Physica Polonica A
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1998
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vol. 94
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issue 3
492-496
EN
Al_{0.3}Ga_{0.7}As layers were grown by molecular beam epitaxy using substrate temperature 200-300°C, tetrameric As and two values of As/Ga+Al flux ratio i.e. 3 or 8. The post-growth annealing was performed in situ at 600°C for 20 min under As-overpressure. The samples were characterised by reflection high-energy electron diffraction, transmission electron microscope and room-temperature I-V measurements of n^{+}/LT grown layer /n^{+} resistors. The resistivity and trap-filled limited voltage have been determined. The best layers exhibited ρ of the order of 10^{9} Ω cm, were monocrystalline, uniformly precipitated and without dislocations.
2
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Photoreflectance Studies of InGaAs/GaAs/AlGaAs Single Quantum Well Laser Structures

100%
Ochalski T., Żuk J., Regiński K., Bugajski M.
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EN
We report on photoreflectance investigations of strained-layer In_{0.2}Ga_{0.8}As/GaAs/Al_{0.3}Ga_{0.7}As single quantum well laser structures grown by molecular beam epitaxy. All the observed photoreflectance spectral features were assigned to the e-hh transitions with Δn=0. The transition energies were determined and compared to their values calculated within the envelope function approximation. Assuming that one third of the total strain in the central In_{0.2}Ga_{0.8}As layer is relaxed by biaxial deformation of surrounding thin GaAs layers, it is possible to explain reasonably the results of our photoreflectance experiment.
3
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X-Ray and Electron-Optical Characterization of ZnTe/CdTe and ZnTe/GaAs Epitaxial Layers Obtained by the MBE Method

88%
Auleytner J., Dziuba Z., Górecka J., Pełka J., Regiński K.
Acta Physica Polonica A
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1994
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vol. 86
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issue 4
567-574
EN
X-ray diffraction topography (Bragg diffraction) and X-ray rocking curve measurements were used to study the perfection and structural properties of ZnTe epitaxial layers on the CdTe and GaAs substrates. ZnTe epitaxial layers on CdTe were grown by MBE method by using a machine made in the Institute of Physics of the Polish Academy of Sciences. The ZnTe layers on GaAs were produced on the other, factory-made MBE system. The comparison between the X-ray topographical images of the substrate and epitaxial layer shows that imperfections on the substrate surface cause imperfections in the epitaxial layer. The results of double-crystal diffractometry measurements show that the perfection of the layer on the GaAs substrate is higher than that on the CdTe. The presence of microtwining in the ZnTe layer on the CdTe substrate was confirmed by RHEED measurements. The X-ray standing wave fluorescent spectra were also measured for the samples.
4
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Three- versus Two-Dimensional Electron Gas Injection in Resonant Tunnelling

88%
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.
5
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Anomalous Behavior of the Hall Effect in III-V Heterostructures

88%
Dziuba Z., Górska M., Marczewski J., Przesławski T., Regiński K.
Acta Physica Polonica A
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2000
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vol. 97
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issue 2
331-336
EN
The Hall effect and magnetoresistance were measured in the InAs/GaAs heterostructure at temperatures from 300 K down to 3 K, in a magnetic field range from 0.01 to 1.5 T. The anomalous magnetic field dependence of the Hall coefficient in the InAs/GaAs heterostructure in magnetic fields below 0.1 T was explained as due to an extraordinary Hall effect caused by skew scattering on dislocations.
6
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Time-Resolved Microwave Spectroscopy of High Electron Mobility GaAs/AlGaAs Structures

88%
Khachepuridze A., Ivanov V., Godlewski M., Regiński K., Bugajski M.
Acta Physica Polonica A
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1998
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vol. 94
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issue 3
387-391
EN
Mechanism of the optical detection of cyclotron resonance via emission from 2D electron gas in modulation doped quantum wells and in high electron mobility structures of GaAs/AlGaAs is discussed based on the results of time-resolved optical detection of cyclotron resonance. An important role of impact ionization processes is demonstrated. We also show that microwave radiation destroys emission enhancement at the Fermi level and the relevant mechanism is proposed.
7
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Fermi-Edge Singularity in Luminescence Spectra of P-Type Modulation Doped AlGaAs/GaAs Quantum Wells

76%
Bugajski M., Godlewski M., Regiński K., Holtz P., Bergman J., Monemar B.
Acta Physica Polonica A
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1998
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vol. 94
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issue 2
265-270
EN
We have studied an enhancement of the oscillator strength for optical transitions near the Fermi energy in p-type modulation-doped quantum wells, which, so far, deserved much less attention than analogous n-type systems, because of the complicated valence band structure involved. The relatively wide (L=150 Å) quantum wells and high doping levels were used, containing more than one occupied subband. The enhancement in the photoluminescence intensity at the Fermi energy resulted from the strong correlation and multiple scattering of holes near the Fermi edge by the localized electrons.
8
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Inter-Island Energy Transfer in AlGaAs/GaAs Quantum Wells Grown by Molecular Beam Epitaxy

76%
Godlewski M., Holz P., Bergman J., Monemar B., Regiński K., Bugajski M.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
1007-1011
EN
The results of photoluminescence, time-resolved photoluminescence, photoluminescence excitation and photoluminescence kinetics studies are presented for a Al_{0.3}Ga_{0.7}As/GaAs quantum well system grown without growth interruptions at the interfaces. The time-resolved photoluminescence measurements show drift of excitons towards lower energy states induced in a quantum well by potential fluctuations. We present also a first direct evidence for migration of free excitons from the 24 to 25 ML regions of the quantum well and interpret these results within a linear rate model, deriving the transition rate of 290 ps^{-1}. Such inter-island migration processes have been observed till now only in growth interrupted structures.
9
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Influence of Growth Conditions on Exciton Properties in Thin Quantum Wells of GaAs/AlGaAs

76%
Godlewski M., Bergman J. P., Holtz P. O., Monemar B., Bugajski M., Regiński K., Kaniewska M.
Acta Physica Polonica A
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1995
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vol. 88
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issue 4
719-722
EN
Exciton properties in growth interrupted quantum wells of GaAs/AlGaAs are compared with those observed for structures grown with­out growth interruption during the molecular beam epitaxy process. We report observation of quasi-localized excitons in quantum well structures grown without growth interruptions. Quasi-localized excitons drift towards the states of a lower potential energy in the quantum well. For growth in­terrupted MBE structures islands with a constant quantum well thickness become large compared to the exciton radius. Free or lightly localized exci­tons are observed in that case.
10
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X-Ray and Electron-Optical Characterization of ZnSe(Co) Crystal with Natural Face

76%
Auleytner J., Domagała J., Gołacki Z., Pawłowska M., Pełka J., Regiński K.
Acta Physica Polonica A
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1993
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vol. 83
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issue 6
759-768
EN
Using complementary X-ray and electron-optical methods, a ZnSe(Co) crystal with natural face was investigated. X-ray diffraction methods such as double-crystal X-ray reflection topography, double-crystal diffractometry for rocking curve measurements, precise lattice constant measurements by the Bond technique were used for crystal structure characterization and X-ray fluorescence method for studies of chemical composition along the crystal. The scanning electron microscopic image of the crystal surface and reflection diffraction of the high-energy electrons enriched the crystal structure characterization. It was shown that X-ray characterization and reflection high-energy electron diffraction can be regarded as very important complementary tools for non-destructive investigation of the ZnSe(Co) crystal surface layers.
11
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Content available

Fine Diffraction Effects in Si Single Crystals Implanted with Fast Ar Ions and Annealed

76%
Żymierska D., Godwod K., Adamczewska J., Auleytner J., Choiński J., Regiński K.
Acta Physica Polonica A
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2002
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vol. 101
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issue 5
743-750
EN
The paper presents high-resolution X-ray diffraction studies performed for Si single crystal: as-grown, implanted with a 5×10^{14} ions· cm^{-2} dose of 3 MeV/n Ar ions, as well as implanted and annealed in a very high vacuum. The results are discussed on the basis of rocking curves and the mathematical analysis of the reciprocal space maps. It is shown that the lattice parameter is increased in an implanted part of the crystal, but long distance lattice curvature is not present. After annealing full relaxation of the crystal is stated.
12
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Fermi-Edge Singularity in Excitonic Spectra of Modulation Doped AlGaAs/GaAs Quantum Wells

76%
Bugajski M., Regiński K., Godlewski M., Wesołowski M., Holtz P., Buyanov A., Monemar B.
Acta Physica Polonica A
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1996
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vol. 90
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issue 4
751-754
EN
The dynamic response of an electron Fermi sea to the presence of optically generated holes gives rise to an enhanced interaction of correlated electron-hole pairs near the Fermi level, resulting in an enhanced oscillator strength for optical transitions, referred to as the Fermi-edge singularity. We studied this effect in modulation-doped quantum wells which provide confined dense Fermi sea, spatially separated from dopant atoms, easily accessible for investigations under low excitation conditions. The Fermi-edge singularity was observed in both photoluminescence and photoluminescence excitation experiments, although in the case of photoluminescence the samples had to be either co-doped with acceptors in the wells to provide necessary localization of holes or designed to allow for nearly resonant scattering between the electronic states near the Fermi energy and the next unoccupied subband of the 2D electron gas.
13
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Low Threshold Room Temperature AlGaAs/GaAs GRIN SCH SQW Lasers Grown by MBE

64%
Kaniewska M., Regiński K., Muszalski J., Kryńska D., Litkowiec A., Kaniewski J., Wesołowski M., Bugajski M.
Acta Physica Polonica A
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1996
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vol. 90
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issue 4
847-850
EN
Low threshold room temperature AlGaAs/GaAs graded-index separate-confinement heterostructure single quantum well (GRIN SCH SQW) lasers were prepared by MBE. The influence of the growth temperature on the laser parameters was studied. Due to the high temperature MBE growth and the use of p-contact layer in the form of thin quasi-metallic beryllium layer significant reduction of the threshold current was achieved.
14
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Identification of Residual Impurities in Si-Doped MBE Grown GaAs

64%
Kaniewska M., Regiński K., Kaniewski J., Muszalski J., Ornoch L., Adamczewska J., Marczewski J., Bugajski M., Mizera E.
Acta Physica Polonica A
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1995
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vol. 88
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issue 4
775-778
EN
The changes of dopant vaporization enthalpy in GaAs:Si grown by mole­cular beam epitaxy revealed the presence of residual donors related to group VI elements. This has been confirmed by deep level transient spectroscopy studies of AlGaAs:Si layers grown in the same MBE system. It is argued that a commonly observed deep trap labelled E2 is probably related to Te, Se or S. The measurements have been performed on near-ideal Al Schottky barriers grown in situ by MBE.
15
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X-ray Study of Strain Relaxation in Heteroepitaxial AlGaAs Layers Annealed under High Hydrostatic Pressure

64%
Bąk-Misiuk J., Adamczewska J., Misiuk A., Regiński K., Wierzchowski W., Wieteska K., Kozanecki A., Kuritsyn D., Glukhanyuk W., Trela J.
Acta Physica Polonica A
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2002
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vol. 101
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issue 5
689-699
EN
The effect of treatment at up to 1270 K under hydrostatic argon pressure, up to 1.2 GPa, on strain relaxation of AlGaAs layers was investigated by X-ray diffraction and related methods. The 1.5μm thick AlGaAs layers were grown by molecular beam epitaxy method on 001 oriented semi-insulating GaAs substrate at 950 K. An increase in intensity of X-ray diffuse scattering, originating from hydrostatic pressure-induced misfit dislocations, was observed for all treated samples. For the samples treated at 920 K during 1 h under 0.6 GPa, the diffuse scattering was confined to the [110] crystallographic direction perpendicular to the direction of dislocations. For the samples treated at 1.2 GPa at the same temperature and time conditions as for 0.6G Pa, a different behaviour is observed, namely the diffuse scattering extends along all azimuthal directions, indicating that dislocations are created in both [110] and [¯110] directions. The change of strain after the treatment was most pronounced for the samples treated at 1.2 GPa for 1 h at 920 K.
16
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Effect of Doping on Ga_{1-x}Al_{x}As Structural Properties

64%
Bąk-Misiuk J., Domagała J., Paszkowicz W., Trela J., Żytkiewicz Z. R., Leszczyński M., Regiński K., Muszalski J., Härtwig J., Ohler M.
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EN
The microstructure of Ga_{1-x}Al_{x}As layers was studied using methods of high resolution diffractometry and topography. Mapping out the reciprocal space in the vicinity of 004 reciprocal lattice points shows a difference in diffuse scattering between doped and undoped layers. This result is attributed to a difference in a point-defect density. From the measurements of lattice parameters at different temperature it was found that the thermal expansion coefficients for the doped layers are higher than for the undoped ones. This phenomenon is attributed to the change of the anharmonic part of lattice vibrations by free electrons or/and point defects.
17
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Content available

High power QW SCH InGaAs/GaAs lasers for 980-nm band

52%
Bugajski M., Mroziewicz B., Regiński K., Muszalski J., Kosiel K., Zbroszczyk M., Ochalski T., Piwoński T., Wawer D., Szerling A., Kowalczyk E., Wrzesińska H., Górska M.
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2005
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vol. 53
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issue 2
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