| 1. |
- Lawniczak-Jablonska, K., et al.
(författare)
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Structural and magnetic properties of GaAs:(Mn,Ga)As granular layers
- 2011
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Ingår i: Physica Status Solidi. B: Basic Research. - : Wiley. - 0370-1972. ; 248:7, s. 1609-1614
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Tidskriftsartikel (refereegranskat)abstract
- Granular GaAs:(Mn,Ga)As films were prepared by annealing the Ga0.92Mn0.08As/GaAs layer grown by the MBE method at low temperature. The annealing was performed at 500 or 600 degrees C. It is commonly accepted that this processing should result in formation of cubic zinc blende or hexagonal MnAs inclusions depending on the temperature. We demonstrate that such a priory assumption is not justified. The kind of formed inclusions depends not only on the annealing temperature but also on the number of defects and Mn atoms in the substitutional and interstitial positions in as grown sample. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 2. |
- Lawniczak-Jablonska, K., et al.
(författare)
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Structural and magnetic properties of nanoclusters in GaMnAs granular layers
- 2011
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596. ; 184:6, s. 1530-1539
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Tidskriftsartikel (refereegranskat)abstract
- Structural and magnetic properties of GaAs thin films with embedded nanoclusters were investigated as a function of the annealing temperature and Mn content. Surprisingly, the presence of two kinds of nanoclusters with different structure was detected in most of the samples independently of the thermal processing or Mn content. This proved that the presence of a given type of clusters cannot be assumed a priori as is reported in many papers. The fraction of Mn atoms in each kind of cluster was estimated from the extended X-ray absorption fine structure analysis. This analysis ruled out the possibility of the existence of nanoclusters containing a hypothetic MnAs cubic compound-only (Ga,Mn)As cubic and hexagonal MnAs clusters were detected. Moreover the bimodal distribution of Mn magnetic moments was found, which scales with the estimated fraction of Mn atoms in the cubic and hexagonal clusters. (C) 2011 Elsevier Inc. All rights reserved.
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| 3. |
- Bak-Misiuk, J., et al.
(författare)
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Creation of MnAs nanoclusters during processing of GaMnAs
- 2009
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Ingår i: Radiation Physics And Chemistry. - : Elsevier BV. - 0969-806X. ; 78, s. 116-119
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Konferensbidrag (refereegranskat)abstract
- GaMnAs layers on (0 0 1)-oriented GaAs substrates were grown by the molecular beam epitaxy (MBE) method. Structural properties of samples processed at up to 920 K under hydrostatic Ar pressure up to 1.1 GPa were investigated by X-ray, secondary ion mass spectroscopy and atomic force microscopy methods. The sign of strain (compressive or tensile) of the GaMnAs layers, related to a creation of MnAs nanoclusters, is found to be dependent on processing conditions and on primary structure defects, whereas it was independent of Mn concentration. An influence of the defects structure in as-grown samples on the strain state of processed GaMnAs layers is discussed. (C) 2009 Elsevier Ltd. All rights reserved.
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| 4. |
- Bak-Misiuk, J., et al.
(författare)
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Pressure Variation of the Strain State of MnAs Nanoclusters Embedded in GaAs
- 2012
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Ingår i: Acta Physica Polonica. Series A: General Physics, Physics of Condensed Matter, Optics and Quantum Electronics, Atomic and Molecular Physics, Applied Physics. - 0587-4246. ; 121:4, s. 903-905
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Tidskriftsartikel (refereegranskat)abstract
- Granular GaAs:(Mn,Ga)As films were prepared by annealing at 500 degrees C under ambient and enhanced hydrostatic pressure (1.1 GPa), of Ga1-xMnxAs/GaAs layers (x = 0.025, 0.03, 0.04, 0.05 and 0.063) grown at 230 degrees C by molecular beam epitaxy method. Distinct influence of enhanced hydrostatic pressure applied during sample annealing on strain state of inclusions was found. An increase of lattice distortion and of strain of inclusions for the samples treated under hydrostatic pressure is related to different bulk moduli of GaAs and of MnAs
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| 5. |
- Bak-Misiuk, J., et al.
(författare)
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Variation of strain in granular GaAs:MnAs layers
- 2013
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Ingår i: Crystallography Reports. - 1063-7745. ; 58:7, s. 998-1001
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Tidskriftsartikel (refereegranskat)abstract
- Granular GaAs(MnAs) layers with different Mn concentration and various layer thickness were grown by MBE method and subjected to annealing at 500A degrees C under ambient and enhanced hydrostatic pressure. Distinct influence of hydrostatic pressure applied during annealing on strain state of layers as well as on hexagonal MnAs inclusions was found. Pressure induced strain of inclusions is related to different bulk moduli of GaAs and of hexagonal MnAs. Formation of hexagonal inclusions depends on concentration of Mn in interstitial position in as-grown samples.
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| 6. |
- Murin, L I, et al.
(författare)
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Thermal double donor annihilation and oxygen precipitation at around 650 degrees C in Czochralski-grown Si: local vibrational mode studies
- 2005
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 1361-648X .- 0953-8984. ; 17:22, s. 2237-2246
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Tidskriftsartikel (refereegranskat)abstract
- We have used local vibrational mode (LVM) spectroscopy to monitor the formation of oxygen-related thermal double donors (TDDs) at 45 0 degrees C and their annihilation at 650 degrees C in carbon-lean Czochralski-grown (Cz-) Si crystals. A few samples were treated at 650 degrees C under high hydrostatic pressure. It is found that the annihilation of TDDs at 650 degrees C results not only in a partial recovery of the interstitial oxygen, but also in the appearance of a number of new O-related LVM bands in the range 990-1110 cm(-1). The positions of these lines and their shapes are identical to those observed for Cz-Si irradiated with electrons or neutrons and annealed at 600-700 degrees C. Since the lines appear upon annealing out of VO3 and VO4 defects in irradiated samples, they are suggested to arise from VOm (m > 4) complexes. In both kinds of samples, pre-annealed and preirradiated, the new LVM bands disappear upon prolonged annealing at 650 degrees C while enhanced oxygen precipitation occurs. The VOm defects are suggested to serve as nuclei for oxygen precipitates developing at around 650 degrees C. High hydrostatic pressure is found to enhance further (up to 4-5 times) the oxygen precipitation process at 650 degrees C in the samples pre-annealed at 450 degrees C.
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| 7. |
- Wolska, A., et al.
(författare)
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Structural and magnetic properties of Mn(+) implanted silicon crystals studied using X-ray absorption spectroscopy techniques
- 2011
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Ingår i: Radiation Physics and Chemistry. - : Elsevier BV. - 0969-806X .- 1879-0895. ; 80:10, s. 1119-1124
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Tidskriftsartikel (refereegranskat)abstract
- The implantation of Mn ions into two Si substrates with different doping (P or B), resistivity and oxygen content was performed at low and high substrate temperatures. Different post-implantation processing was carried out to study its influence on the structural and magnetic properties of these samples. The local order around the Mn atoms was characterized by X-ray absorption fine structure techniques and the magnetic properties of the Mn ionic cores were determined by means of X-ray magnetic circular dichroism measurements. The results are discussed in relation to the structural and macroscopic magnetic properties. It is shown that the amorphous matrix speeds up the formation of MnSi(x) inclusions. However, the existence of inclusions or the type of electrically active dopants is not directly related to the magnetic properties. Therefore, in the performed studies, the importance of structural defects on the magnetic properties was confirmed. A localized magnetic moment carried by the Mn ionic cores could not be detected by means of dichroic measurements.
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| 8. |
- Dynowska, E., et al.
(författare)
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Structural and magnetic properties of GaSb:MnSb granular layers
- 2011
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Ingår i: Radiation Physics and Chemistry. - : Elsevier BV. - 0969-806X. ; 80:10, s. 1051-1057
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Konferensbidrag (refereegranskat)abstract
- The results of structural and magnetic characterization of GaMnSb layers grown on GaSb(0 0 1) and GaAs(1 1 1) substrates are presented. The presence of hexagonal, highly oriented MnSb inclusions embedded in GaSb matrix has been demonstrated. The lattice parameters of these inclusions were the same as those for bulk MnSb for the layers grown on GaSb(1 0 0) substrate while for the layers grown on GaAs(1 1 1) the MnSb inclusions were strained. The influence of a presence of MnSb clusters on the lattice parameter of GaSb matrix has been demonstrated. It was confirmed that in all cases the MnSb clusters exhibit a ferromagnetic: behavior at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.
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| 9. |
- Murin, LI, et al.
(författare)
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Effect of high hydrostatic pressure on small oxygen-related clusters in silicon: LVM studies
- 2003
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Ingår i: Physica B: Condensed Matter. - : Elsevier BV. - 0921-4526. ; 340, s. 565-569
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Tidskriftsartikel (refereegranskat)abstract
- Local vibrational mode (LVM) spectroscopy is used to explore the effect of high hydrostatic pressure (HP) on the formation of small oxygen-related clusters (dimers, trimers, thermal donors, and C-O complexes) at 450degreesC and 650degreesC in Cz-Si crystals with different impurity content and prehistory. It is found, in agreement with previous studies, that HP enhances the oxygen clustering in Cz-Si at elevated temperatures. The effect of HP is related mainly to enhancement in the diffusivity of single oxygen atoms and small oxygen aggregates. HP does not noticeably increase the binding energies of the most simple oxygen related complexes like O-2i, CsOm. The biggest HP effect on the thermal double donor (TDDs) generation is revealed in hydrogenated samples. Heat-treatment of such samples at 450degreesC under HP results in extremely high TDD introduction rates as well as in a strong increase in the concentration of the first TDD species. (C) 2003 Elsevier B.V. All rights reserved.
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| 10. |
- Romanowski, P., et al.
(författare)
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Defect Structure of High-Temperature-Grown GaMnSb/GaSb
- 2010
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Ingår i: Acta Physica Polonica A. - 0587-4246. ; 117:2, s. 341-343
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Konferensbidrag (refereegranskat)abstract
- GaMnSb/GaSb(100) layers with embedded MnSb inclusions have been grown at 720 K using MBE technique. This paper presents the investigation of the defect structure of Ga1-xMnxSb layers with different content of manganese (up to x = 0.07). X-ray diffraction method using conventional and synchrotron radiation was applied. Dimensions and shapes of inclusions were detected by scanning electron microscopy. Depth profiles of elements were measured using secondary ion mass spectroscopy technique.
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