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Nanostructure of Si-Ge Near-Surface Layers Produced by Ion Implantation and Laser Annealing

100%
Klinger D., Kret S., Auleytner J., Żymierska D.
Acta Physica Polonica A
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2002
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vol. 102
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issue 2
259-264
EN
An annealing with the nanosecond laser light pulse is applied for crystal lattice reconstruction of a disturbed near-surface layer, which was created in semiconductor material as a result of the implantation process. Radiation with energy density higher than the threshold value causes the melting of the surface layer and then the epitaxial recrystallization from the melt on a different substrate. Structural changes occurring in the Ge implanted Si crystals after annealing with different energy densities are investigated by means of the cross-section high-resolution transmission electron microscopy.
2
Content available remote

In Situ Electron Beam Amorphization of Sb₂Te₃ within Single Walled Carbon Nanotubes

88%
Marks S., Morawiec K., Dluzewski P., Kret S., Sloan J.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1324-1327
EN
In this study, we reveal the crystallography, crystallinity, and amorphization of low-dimensional crystals of the topological insulator and phase change material Sb₂Te₃ within both discrete and bundled single walled carbon nanotubes with a diameter range spanning 1.3-1.7 nm by a combination of electron diffraction, aberration-corrected high resolution imaging, and variable dose electron beam irradiation. We further reveal that electron diffraction indicates that the crystallinity of the host single walled carbon nanotubes is largely unaffected by this process indicating that mass loss during the observed in situ glass transition had not occurred and that the template had maintained its structural integrity. Such a transition would not be possible with any other common nanoporous template for which the pores would be enlarged due to likely sintering.
3
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Strain Relaxation of ZnTe/CdTe and CdTe/ZnTe heterostructures: In Situ Study

88%
Riesz F., Kret S., Karczewski G., Wojtowicz T., Kossut J.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
911-914
EN
The strain relaxation kinetics of ZnTe/CdTe and CdTe/ZnTe heterostructures grown on GaAs substrates by molecular beam epitaxy are studied by in situ reflection high-energy electron diffraction. The observed critical layer thickness is 5 monolayers for ZnTe/CdTe and less than 1 monolayer for CdTe/ZnTe. The relaxation is anisotropic. Dislocation core parameters and relaxation rate constants were determined using a kinetic model and assuming strain-dependent activation energy of dislocation movement.
4
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FIB Method of Sectioning of III-V Core-Multi-Shell Nanowires for Analysis of Core/Sell Interfaces by High Resolution TEM

76%
Kret S., Kaleta A., Bilska M., Kurowska B., Siusys A., Dąbrowski J., Sadowski J.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1332-1335
EN
The core-multishell wurtzite structure (In,Ga)As-(Ga,Al)As-(Ga,Mn)As semiconductor nanowires have been successfully grown on GaAs(111)B substrates using MBE technique. The nanowires cores were grown with gold eutectic catalyser in vapour-liquid-solid growth mode. The double shell overgrowth, on the side facets of nanowires, was performed using lower substrate temperature (about 400°C, and 230°C, for (Ga,Al)As, and (Ga,Mn)As shell growth, respectively). The polytypic ordering, defects, chemistry and geometric perfection of the core and the shells have been analysed at atomic level by advanced transmission electron microscope techniques with the use of axial and longitudinal section of individual nanowires prepared by focused ion beam. High quality cross-sections suitable for quantitative transmission electron microscope analysis have been obtained and enabled analysis of interfaces between the core and the shells with near atomic resolution. All investigated shells are epitaxial without misfit dislocations at the interface. Some of the shells thicknesses are not symmetric, which is due to the shadowing effects of neighbouring nanowires and directional character of the elemental fluxes in the MBE growth process.
5
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Application of Graphics Processing Unit for In-Line Electron Holography

76%
Morawiec K., Dłużewski P., Kret S., Szczepańska A., Li T., Sloan J.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1353-1356
EN
In the present work, software for exit electron wave reconstruction based on the iterative approach was implemented and a new method for drift-correction of the focal series was proposed.
6
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Off-Axis Electron Holography of Magnetic Nanostructures: Magnetic Behavior of Mn Rich Nanoprecipitates in (Mn,Ga)As System

76%
Barańska M., Dłużewski P., Kret S., Morawiec K., Li T., Sadowski J.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1406-1408
EN
The Lorentz off-axis electron holography technique is applied to study the magnetic nature of Mn rich nanoprecipitates in (Mn,Ga)As system. The effectiveness of this technique is demonstrated in detection of the magnetic field even for small nanocrystals having an average size down to 20 nm.
7
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Impact of Thin LT-GaN Cap Layers on the Structural and Compositional Quality of MOVPE Grown InGaN Quantum Wells Investigated by TEM

76%
Ivaldi F., Kret S., Szczepańska A., Czernecki R., Kryśko M., Grzanka S., Leszczyński M.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
660-662
EN
Two samples containing InGaN quantum wells have been grown by metal-organic vapor phase epitaxy on high pressure grown monocrystalline GaN (0001). Different growth temperatures have been used to grow the wells and the barriers. In one of the samples, a low temperature GaN layer (730°C) has been grown on every quantum well before rising the temperature to standard values (900°C). The samples have been investigated by transmission electron microscopy and X-ray diffraction. Photoluminescence spectra have been measured as well. The influence of the LT-GaN has been investigated in regard to its influence on the structural and compositional quality of the sample.
8
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Digital Magnetic Quantum Wells for the Study of Interface Sharpness of Molecular Beam Epitaxy Grown Structures

64%
Wojtowicz T., Karczewski G., Żakrzewski A., Kutrowski M., Janik E., Dynowska E., Kopalko K., Kret S., Kossut J., Laval J.
Acta Physica Polonica A
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1995
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vol. 87
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issue 1
165-168
EN
We report on the growth and basic characterization of digital magnetic quantum wells, that is, quantum wells in which the well material is itself a short period superlattice composed of alternating diluted magnetic and nonmagnetic semiconductor layers each only a few monolayers thick. These novel structures can be useful in a variety of studies, including studies of barrier-well interface sharpness.
9
Content available remote

Lattice Parameter Relaxation during MBE of ZnTe/Cd_{1-x}Zn_{x}Te/Cd_{0.5}Zn_{0.5}Te Buffer Layers by RHLED and HRTEM

64%
Kret S., Karczewski G., Zakrzewski A., Dłużewski P., Dubon A., Wojtowicz T., Kossut J., Delamarre C., Laval J. Y.
Acta Physica Polonica A
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1995
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vol. 88
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issue 4
795-798
EN
The dynamics of the lattice relaxation processes were investigated us­ing a reflection of a high energy electron diffraction analysis system dur­ing growth by molecular beam epitaxy of ZnTe/Cd_{1-x}Ζn_{x}Te/Cd_{0.5}Mn_{0.5}Te buffers on GaAs substrates. The variation of the lattice parameter recorded by the high energy electron diffraction during the growth was later confirmed by an analysis of high resolution transmission electron microscopy images. We report also on an observation of oscillations of the lattice parameter during the deposition of several first layers of ZnTe on CdTe.
10
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TEM Study of the Structural Properties of Nanowires Based on Cd, Zn, Te grown by MBE on Silicon Substrates

64%
Kaleta A., Kret S., Sanchez A., Bilska M., Kurowska B., Szczepańska A., Płachta J., Wojnar P., Wojciechowski T.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1399-1405
EN
In this work we report on the atomic structures, elemental distribution, defects and dislocations of three types of semiconductor nanowires: ZnTe, CdTe, and complex ZnTe/(Cd,Zn)Te core/shell hetero-nanowires grown by a molecular beam epitaxy on (111) Si substrate using a vapor-liquid-solid mechanism. The structural properties and the chemical gradients were measured by transmission electron microscopy methods. The nanowires reveal mainly sphalerite structure, however wurtzite nanowires were also observed.
11
Content available remote

Neutral and Charged Excitons Localized in the InAs/GaAs Wetting Layer

64%
Babiński A., Czyż M., Golnik A., Borysiuk J., Kret S., Raymond S., Lapointe J., Wasilewski Z.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1055-1060
EN
It has recently been shown that potential fluctuations in a wetting layer, which accompanies InAs/GaAs quantum dots can localize excitons. Neutral excitons and biexcitons and charged excitons were identified. In this communication we report on studies of properties of the excitons over wide temperature range (T < 70 K). The micro-photoluminescence measurements enable investigation of excitons localized in a single potential fluctuation. Temperature-induced broadening of the neutral exciton as well as a quenching of the charged exciton at temperatures higher than 50 K are observed and discussed.
12
Content available remote

Morphology and Selected Properties of Core/Shell ZnTe-Based Nanowire Structures Containing ZnO

52%
Gas K., Janik E., Zaleszczyk W., Pasternak I., Dynowska E., Fronc K., Kolkovsky V., Kret S., Morhange J., Reszka A., Wiater M., Caliebe W., Karczewski G., Kowalski B., Szuszkiewicz W., Wojtowicz T.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
612-614
EN
We report on an approach to fabricate ZnTe-based core/shell radial heterostructures containing ZnO, as well as on some of their physical properties. The molecular beam epitaxy grown ZnTe nanowires constituted the core of the investigated structures and the ZnO shells were obtained by thermal oxidation of ZnTe NWs. The influence of the parameters characterizing the oxidation process on selected properties of core/shell NWs were examined. Scanning electron microscopy revealed changes of the NWs morphology for various conditions of the oxidation process. X-ray diffraction, high resolution transmission electron microscopy, and Raman scattering measurements were applied to reveal the presence of ZnTe single crystal core and polycrystalline ZnO-shell of investigated structure.
13
Content available remote

Photoluminescence Properties of ZnO and ZnCdO Nanowires

52%
Zaleszczyk W., Fronc K., Aleszkiewicz M., Paszkowicz W., Wróbel J., Dłużewski P., Kret S., Klepka M., Kłopotowski Ł., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
357-362
EN
We report on the photoluminescence studies of ZnO and ZnCdO nanowires grown on SiO_2/Si substrates by low-pressure vapor phase synthesis. X-ray diffraction and transmission electron microscopy measurements show that the crystallographic structure of these ZnO and ZnCdO nanowires is of wurtzite-type with a high crystal perfection. Surface morphology of samples was determined by scanning electron microscopy and atomic force microscopy. The photoluminescence spectra of as-grown nanowires, nanowires extracted from the substrate and deposited onto Si wafer, and nanowires dispersed in ethanol by sonication were investigated at room temperature and compared to each other. The temperature dependence of the near band-gap photoluminescence emitted by the as-grown nanowires was also measured and analyzed.
14
Content available remote

Growth and Properties of ZnMnTe Nanowires

46%
Zaleszczyk W., Janik E., Presz A., Szuszkiewicz W., Morhange J., Dłużewski P., Kret S., Kirmse H., Neumann W., Dynowska E., Domagała J., Caliebe W., Aleszkiewicz M., Pacuski W., Golnik A., Kossacki P., Baczewski L., Petroutchik A., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
351-356
EN
Catalytically enhanced growth of ZnMnTe diluted magnetic semiconductor nanowires by molecular beam epitaxy is reported. The growth is based on the vapor-liquid-solid mechanism and was performed on (001) and (011)-oriented GaAs substrates from elemental sources. X-ray diffractometry, scanning and transmission electron microscopy, atomic force microscopy, photoluminescence spectroscopy, and Raman scattering were performed to determine the structure of nanowires, their chemical composition, and morphology. These studies revealed that the obtained ZnMnTe nanowires possess zinc-blende structure, have an average diameter of about 30 nm, typical length between 1 and 2μm and that Mn^{2+} ions were incorporated into substitutional sites of the ZnTe crystal lattice.
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