CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, PL-01142 Warsaw, Poland International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw,... more
CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, PL-01142 Warsaw, Poland International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw, Poland. Laboratoire Charles Coulomb, Université de Montpellier, Centre National de la Recherche Scientifique, F-34095 Montpellier, France. Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw, Poland. Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent’eva 13, Novosibirsk, 630090 Russia. Institute for Physics of Microstructures, Russian Academy of Sciences, N. Novgorod, 603950 Russia. WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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The finite element modeling is used to improve the accuracy of In composition determination by taking into account the two limiting factors in high resolution microscopy: strain relaxation and projection.
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A new technique for studying extended defects and dislocation networks is proposed. The approach, based upon the continuum theory of crystal defects, is employed for digital image processing of high-resolution transmission electron... more
A new technique for studying extended defects and dislocation networks is proposed. The approach, based upon the continuum theory of crystal defects, is employed for digital image processing of high-resolution transmission electron micrographs. The procedure starts ...
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CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is... more
CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.
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The effect of Cu ion doping on the photoluminescence (PL) and magnetic behavior of ZnO/MgO and ZnO/oleic acid core/shell nanoparticles is investigated.
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We report on Au catalyst-assisted molecular beam epitaxy growth and properties of pure ZnSe and ZnSe/CdSe superlattice nanowires. In particular, we concentrate our attention on the morphological characterization by transmission and... more
We report on Au catalyst-assisted molecular beam epitaxy growth and properties of pure ZnSe and ZnSe/CdSe superlattice nanowires. In particular, we concentrate our attention on the morphological characterization by transmission and scanning electron microscopy of pure ZnSe NWs and we compare their optical properties with those of ZnSe/CdSe superlattice NWs fabricated at the same technological conditions.
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ZnTe nanowires produced by molecular beam epitaxy via the vapour/liquid/solid mechanism were studied by transmission electron microscopy. The wires grew along the ?111? directions pointing out of the (001)-oriented GaAs substrate. The... more
ZnTe nanowires produced by molecular beam epitaxy via the vapour/liquid/solid mechanism were studied by transmission electron microscopy. The wires grew along the ?111? directions pointing out of the (001)-oriented GaAs substrate. The length of the wires amounted to some microns depending on the growth time. The mean diameter ranged between 30 and 60 nm depending on the size of the
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ABSTRACT MBE grown ZnTe/CdxZn1-xTe superlattices containing a high density of quantum dots have been investigated by quantitative TEM methods. The Cd concentration in the superlattice was determined from local lattice parameter measured... more
ABSTRACT MBE grown ZnTe/CdxZn1-xTe superlattices containing a high density of quantum dots have been investigated by quantitative TEM methods. The Cd concentration in the superlattice was determined from local lattice parameter measured by digital processing of experimental HRTEM images. For the 15ML(ZnTe)/2ML(CdTe) superlattice, the density of quantum dots is 1.3x106 P-3. The dots are Cd rich islands of diameter from 6 to 8 nm and hights below 1.5 nm. The Cd concentration in islands centre was estimated to be between x=0.35 and x=0.85. Areas with ordering of QD were observed.
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An arrangement of self-assembled GaN nanowires (NWs) grown by plasma-assisted molecular beam epitaxy on a Si(111) substrate is studied as a function of the temperature at which the substrate is nitridized before GaN growth. We show that... more
An arrangement of self-assembled GaN nanowires (NWs) grown by plasma-assisted molecular beam epitaxy on a Si(111) substrate is studied as a function of the temperature at which the substrate is nitridized before GaN growth. We show that the NWs grow with the c-axis perpendicular to the substrate surface independently of nitridation temperature with only a slight improvement in tilt coherency for high nitridation temperatures. A much larger influence of the substrate nitridation process on the in-plane arrangement of NWs is found. For high (850 °C) and medium (450 °C) nitridation temperatures angular twist distributions are relatively narrow and NWs are epitaxially aligned to the substrate in the same way as commonly observed in GaN on Si(111) planar layers with an AlN buffer. However, if the substrate is nitridized at low temperature (~150 °C) the epitaxial relationship with the substrate is lost and an almost random in-plane orientation of GaN NWs is observed. These results are correlated with a microstructure of silicon nitride film created on the substrate as the result of the nitridation procedure.
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Research Interests: Condensed Matter Physics, Materials Science, Crystallization, Nanowire, Nanotechnology, and 15 moreMedicine, Multidisciplinary, Manganese, Molecular beam epitaxy, Nanowires, Nanostructures, Magnetic Properties, Particle Size, Phase Separation, Epitaxy, Molecular Conformation, Gallium, Materials Testing, Arsenicals, and Heavy Ions
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The structure of GaMnAs nanowires (NW) with nominal Mn concentration of up to 7 at% was investigated by transmission electron microscopy. The (Ga,Mn)As NW were grown on epiready GaAs(001) n-type wafers by molecular beam epitaxy. The... more
The structure of GaMnAs nanowires (NW) with nominal Mn concentration of up to 7 at% was investigated by transmission electron microscopy. The (Ga,Mn)As NW were grown on epiready GaAs(001) n-type wafers by molecular beam epitaxy. The crystal structure of the NW was determined to be zinc-blende. NW with Mn concentrations lower than 5 at% grow along the 111 direction. NW with higher Mn concentrations grow along the 110 direction and reveal a branching structure. The main nanowire and branches grow along the 110 directions belonging to only one {111} plane.
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We report on the formation of optically active CdTe quantum dots in ZnTe nanowires. The CdTe/ZnTe nanostructures have been grown by a gold nanocatalyst assisted molecular beam epitaxy in a vapor-liquid solid growth process. The presence... more
We report on the formation of optically active CdTe quantum dots in ZnTe nanowires. The CdTe/ZnTe nanostructures have been grown by a gold nanocatalyst assisted molecular beam epitaxy in a vapor-liquid solid growth process. The presence of CdTe insertions in ...
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Extracting Quantitative Information from High Resolution Electron Microscopy ... S. Kret*) (a), P. Ruterana 1 ) (a), A. Rosenauer (b), and D. Gerthsen (b) ... (a) ESCTM-CRISMAT, UMR 6508 CNRS, ISMRA, 6 Bd du Maréchal Juin, ...
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ABSTRACT The misfit and threading dislocations during GaSb epitaxy on GaAs substrate were investigated by weak beam dark field and high angle dark field scanning transmission electron microscopy. The geometric phase analysis and... more
ABSTRACT The misfit and threading dislocations during GaSb epitaxy on GaAs substrate were investigated by weak beam dark field and high angle dark field scanning transmission electron microscopy. The geometric phase analysis and dislocation density tensor analysis were next used to analyze the strain around the threading dislocations and quantify the corresponding Burgers vectors. It is shown that there are three types of threading dislocations (mixed, edge, and pair of mixed types) close to the interface, which originate from the 60°, Lomer, and 60° pair misfit dislocations, respectively. During the growth of the epitaxial layer, the edge type as well as the pair of mixed threading dislocations split into two mixed type dislocations for the glide in {111} planes. Eventually, only mixed type dislocations have been observed at the surface of thick GaSb layers.
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4.1. Title of the publication series and the list of publications of which it consists ....... 2 4.2. Bibliometric data.................................................................................................. 3 4.3. Introduction... more
4.1. Title of the publication series and the list of publications of which it consists ....... 2 4.2. Bibliometric data.................................................................................................. 3 4.3. Introduction – scientific background..................................................................... 3 4.3.1. Vapor-liquid-solid growth mechanism of nanowires ....................................... 5 4.3.2. Heterostructures in semiconductor nanowires ................................................. 5 4.3.3. Magnetic ions inside nanowires ...................................................................... 6
Extended abstract of a paper presented at MC 2007, 33rd DGE Conference in Saarbrücken, Germany, September 2 – September 7, 2007
We study nanoscale morphology of PbTe/CdTe multilayer heterostuctures grown by molecular beam epitaxy on hybrid GaAs/CdTe (100) substrates. Nominally, the structures consist of 25 repetitions of subsequently deposited CdTe and PbTe layers... more
We study nanoscale morphology of PbTe/CdTe multilayer heterostuctures grown by molecular beam epitaxy on hybrid GaAs/CdTe (100) substrates. Nominally, the structures consist of 25 repetitions of subsequently deposited CdTe and PbTe layers with comparable thicknesses of 21 and 8 nm, respectively. However, the morphology of the resulting structures crucially depends on the growth temperature. The two-dimensional layered, superlattice-like character of the structures remains preserved only when grown at low substrate temperatures, such as 230 °C. The samples grown at the slightly elevated temperature of 270 °C undergo a morphological transformation to structures consisting of CdTe and PbTe pillars and columns oriented perpendicular to the substrate. Although the pillar-like objects are of various shapes and dimensions these structures exhibit exceptionally strong photoluminescence in the near infrared spectral region. At the higher growth temperature of 310 °C, PbTe and CdTe separate c...
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The absence of luminescence in the near band edge energy region of Te-anion based semiconductor nanowires grown by gold catalyst assisted molecular beam epitaxy has strongly limited their applications in the field of photonics. In this... more
The absence of luminescence in the near band edge energy region of Te-anion based semiconductor nanowires grown by gold catalyst assisted molecular beam epitaxy has strongly limited their applications in the field of photonics. In this paper, an enhancement of the near band edge emission intensity from ZnTe/ZnMgTe core/shell nanowires grown on Si substrates is reported. A special role of the use of Si substrates instead of GaAs substrates is emphasized, which results in an increase of the near band edge emission intensity by at least one order of magnitude accompanied by a simultaneous reduction of the defect related luminescence. A possible explanation of this effect relies on the presence of Ga-related deep level defects in structures grown on GaAs substrates, which are absent when Si substrates are used. Monochromatic mapping of the cathodoluminescence clearly confirms that the observed emission originates, indeed, from the ZnTe/ZnMgTe core/shell nanowires, whereas individual objects are studied by means of microphotoluminescence.
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We report on the first successful growth of ZnTe nanowires and on their basic structural properties. The nanowires were produced by molecular beam epitaxy (MBE) with the use of mechanism of catalytically enhanced growth. A thin layer of... more
We report on the first successful growth of ZnTe nanowires and on their basic structural properties. The nanowires were produced by molecular beam epitaxy (MBE) with the use of mechanism of catalytically enhanced growth. A thin layer of gold layer (3 to 20 Å thick) annealed in high vacuum prior to the nanowires growth was used as a source of
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We report on the growth, cathodoluminescence and micro-photoluminescence of individual radial and axial CdTe insertions in ZnTe nanowires. In particular, the cathodoluminescence technique is used to determine the position of each emitting... more
We report on the growth, cathodoluminescence and micro-photoluminescence of individual radial and axial CdTe insertions in ZnTe nanowires. In particular, the cathodoluminescence technique is used to determine the position of each emitting object inside the nanowire. It is demonstrated that depending on the CdTe deposition temperature, one can obtain an emission either from axial CdTe insertions only, or from both, radial and axial heterostructures, simultaneously. At 350 °C CdTe grows only axially, whereas at 310 °C and 290 °C, there is also significant deposition on the nanowire sidewalls resulting in radial core/shell heterostructures. The presence of Cd atoms on the sidewalls is confirmed by energy dispersive X-ray spectroscopy. Micro-photoluminescence study reveals a strong linear polarization of the emission from both types of heterostructures in the direction along the nanowire axis.
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15 During epitaxy of GaN on sapphire grains form a mosaic structure. The distance between edge dislocations in these boundaries 16 is from 2 to 15 nm. The strain around the dislocations is quantitatively measured by processing of HRTEM... more
15 During epitaxy of GaN on sapphire grains form a mosaic structure. The distance between edge dislocations in these boundaries 16 is from 2 to 15 nm. The strain around the dislocations is quantitatively measured by processing of HRTEM images. The 17 dislocation core distribution maps and in plane Burgers vectors components are derived from the experimental strain tensor by
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Magnetic semiconductor nanowires (NWs) are subject of intense fundamental research due to their potential applicability in the field of spin-based electronics. In general, NWs are several micrometers long and only a few tens of nanometers... more
Magnetic semiconductor nanowires (NWs) are subject of intense fundamental research due to their potential applicability in the field of spin-based electronics. In general, NWs are several micrometers long and only a few tens of nanometers in diameter. Our previous work focussed on the understanding of the structural and chemical properties of ZnTe NWs [1–3]. These NWs were grown on GaAs
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Stacks of InAs self-assembled quantum wires (QWr) grown by solid source molecular beam epitaxy on InP (001) substrates have been studied by both transmission electron microscopy (TEM) and high resolution transmission electron microscopy... more
Stacks of InAs self-assembled quantum wires (QWr) grown by solid source molecular beam epitaxy on InP (001) substrates have been studied by both transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Samples with an InP spacer layer thickness ≤ 10 nm are shown to exhibit stacked quantum wires well arranged along directions close to [001]. The analysis
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Semiconductor nanowires are freestanding one-dimensional objects with a length of some microns and a diameter of few tens of nanometres. Due to this unique shape the electronic states of the nanowires are quantized perpendicularly to the... more
Semiconductor nanowires are freestanding one-dimensional objects with a length of some microns and a diameter of few tens of nanometres. Due to this unique shape the electronic states of the nanowires are quantized perpendicularly to the growth direction. Such semiconductor structures are favourable for numerous applications.