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108 results on '"Bożek, R."'

3. Magnetization Saturation Process in the Magnonic Anti-dot Structures Based on (Ga,Mn)As: A Magnetometric Study

Author

Dziatkowski, K., Staszewski, W. P., Bożek, R., Szczytko, J., Gosk, J., Twardowski, A., Liu, X., and Furdyna, J. K.

Subjects
Condensed Matter - Materials Science
Abstract

Applicability of dilute magnetic semiconductors (DMS) in electronic devices relies upon the understanding and control of their magnetic anisotropy. This paper explores one of the ways in engineering magnetic anisotropy in epitaxial layers of DMS by forming them into magnonic structures. For this purpose the canonical ferromagnetic DMS, namely (Ga,Mn)As, is employed. The anti-dot systems based on (Ga,Mn)As layers of various thicknesses are fabricated with focused ion beam apparatus and studied by means of microscopy as well as magnetometry. The magnetometric data - collected along two nonequivalent in-plane crystallographic directions of (Ga,Mn)As: [110] and [1-10] - shows the effect of structuring on high-field magnetization process, whereas no significant change of the width of hysteresis loop in anti-dot samples is observed., Comment: 5 pages, 6 figures

Published
2016

10. Transmission electron microscopy investigations of epitaxial graphene on C-terminated 4H–SiC.

Author

Borysiuk, J., Bożek, R., Grodecki, K., Wysmołek, A., Strupiński, W., Stępniewski, R., and Baranowski, J. M.

Subjects
*GRAPHENE, *SILICON carbide, *TRANSMISSION electron microscopy, *SUBSTRATES (Materials science), *CARBON
Abstract

Transmission electron microscopy (TEM) investigations of epitaxial graphene, grown on on-axis and 8° off-axis C-terminated 4H–SiC [formula] surfaces are presented. The TEM results provide evidence that the first carbon layer is separated by 3.2 Å from the C-terminated SiC surface. It was also found that thick graphene layers grown on on-axis SiC [formula] are loosely bound to the SiC substrate. Moreover, the structural observations reveal a certain degree of disorder between the graphene planes, which manifests itself in a rotation of the layers and in an increase in the interplanar spacing between certain carbon layers from 3.35 Å, which is characteristic for graphite, up to 3.7 Å. Graphene grown on 8° off-axis SiC [formula] substrates covers the steps of SiC and as a result disorder seems to be not as pronounced as it is on the on-axis SiC [formula] substrate. [ABSTRACT FROM AUTHOR]

Published
2010
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11. Transmission electron microscopy and scanning tunneling microscopy investigations of graphene on 4H-SiC(0001).

Author

Borysiuk, J., Bożek, R., Strupinski, W., Wysmołek, A., Grodecki, K., Polish_hook, R., and Baranowski, J. M.

Subjects
*TRANSMISSION electron microscopy, *SCANNING probe microscopy, *SCANNING tunneling microscopy, *PARTICLES (Nuclear physics), *EPITAXY, *CRYSTAL growth
Abstract

Transmission electron microscopy (TEM), scanning tunneling microscopy (STM), and micro-Raman investigations of epitaxial graphene on 4H-SiC on-axis and 4° off-axis are presented. The STM images show that there is superimposed on 1×1 graphene pattern the carbon nanomesh of honeycomb 6×6 structure with the lattice vector of 17.5 Å. The TEM results give evidence that the first carbon layer is separated by 2 Å from the Si-terminated SiC surface and that subsequent carbon layers are spaced by 3.3 Å. It is also found in TEM that the graphene layers cover atomic steps, present on 4° off-axis SiC(0001) surface, indicating a carpetlike growth mode. However, a bending of graphene planes on atomic steps of SiC apparently leads to generation of stress which leads to creation of edge dislocations in the graphene layers. [ABSTRACT FROM AUTHOR]

Published
2009
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12. Structure and magnetism of MnAs nanocrystals embedded in GaAs as a function of post-growth annealing temperature.

Author

Kwiatkowski, A., Wasik, D., Kaminska, M., Bożek, R., Szczytko, J., Twardowski, A., Borysiuk, J., Sadowski, J., and Gosk, J.

Subjects
NANOCRYSTALS, MAGNETIC properties, MANGANESE compounds, GALLIUM arsenide, ANNEALING of crystals
Abstract

Self-organized Ga(Mn)As nanoclusters, embedded in GaAs, were formed during post-growth thermal annealing of Ga1-xMnxAs layers. Structural and magnetic properties of such composites were systematically studied as a function of the annealing temperature. Small (∼3 nm) Mn-rich zinc-blende Mn(Ga)As clusters, coherent with the GaAs matrix, were formed at the annealing temperature of 500 °C. An increase of the annealing temperature of up to 600 °C led to the creation of 10–20 nm large NiAs-type hexagonal MnAs nanocrystals. Magnetization measurements showed that the MnAs nanoprecipitates were superparamagnetic, with a distribution of blocking temperatures that depended on the MnAs cluster size. Some intermediate paramagnetic clusters (structurally disordered clusters) were also observed. [ABSTRACT FROM AUTHOR]

Published
2007
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29. Micro-analysis of light emission properties of GaN-based laser diodes

Author

Godlewski, M., primary, Bożek, R., additional, Miasojedovas, S., additional, Juršėnas, S., additional, Kazlauskas, K., additional, Žukauskas, A., additional, Phillips, M. R., additional, Czernecki, R., additional, Targowski, G., additional, Perlin, P., additional, Leszczyński, M., additional, Böttcher, T., additional, Figge, S., additional, and Hommel, D., additional

Published
2007
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30. The disorder-induced Raman scattering in Au/MoS2 heterostructures.

Author

Gołasa, K., Grzeszczyk, M., Binder, J., Bożek, R., Wysmołek, A., and Babiński, A.

Subjects
RAMAN scattering, HETEROSTRUCTURES, MOLYBDENUM sulfides, GOLD, PHONONS, RELAXATION phenomena, BRILLOUIN zones, ELECTRONIC excitation
Abstract

The Raman scattering has been studied in heterostructures composed of a thin MoS2 flake and a 1-1.5 nm layer of thermally evaporated gold (Au). There have been Au nanoislands detected in the heterostructure. It has been found that their surface density and the average size depend on the MoS2 thickness. The Raman scattering spectrum in the heterostructure with a few monolayer MoS2 only weakly depends on the excitation (resonant vs. non-resonant) mode. The overall Raman spectrum corresponds to the total density of phonon states, which is characteristic for disordered systems. The disorder in the MoS2 layer is related to the mechanical strain induced in the MoS2 layer by the Au nanoislands. The strain results in the localization of phonon modes, which leads to the relaxation of the momentum conservation rule in the scattering process. The relaxation allows phonons from the whole MoS2 Brillouin zone to interact with electronic excitations. Our results show that the Au nanoislands resulted from thermal evaporation of a thin metal layer introduce substantial disorder into the crystalline structure of the thin MoS2 layers. [ABSTRACT FROM AUTHOR]

Published
2015
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31. MnAs Nanocrystals Embedded in GaAs

Author

Kwiatkowski, A., primary, Borysiuk, J., additional, Bożek, R., additional, Wasik, D., additional, Kamińska, M., additional, Sadowski, J., additional, and Twardowski, A., additional

Published
2006
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37. Influence of n-type doping on light emission properties of GaN layers and GaN-based quantum well structures

Author

Godlewski, M., primary, Ivanov, V. Yu., additional, Łusakowska, E., additional, Bożek, R., additional, Miasojedovas, S., additional, Juršėnas, S., additional, Kazlauskas, K., additional, Žukauskas, A., additional, Goldys, E. M., additional, Phillips, M. R., additional, Böttcher, T., additional, Figge, S., additional, and Hommel, D., additional

Published
2005
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