Wyniki wyszukiwania - Biblioteka Nauki

1

Growth of Ternary and Quaternary ZnSe Compounds with Transition Metals by Chemical Vapor Transport

100%

Janik E. , Grasza K. , Mycielski A. , Bąk-Misiuk J. , Kachniarz J.

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nr 4

785-788

EN

Halogen transport method was applied to grow the crystals of solid solutions of ZnSe and transition metals at the temperature far below the melting point and phase transition temperature. The large crystals of ZnMnSe, ZnFeSe, ZnNiSe and ZnFeSSe were obtained. The technological parameters and shape of the quartz reactor were chosen for growth of a large crystal by self-nucleation; the transparent quartz furnace enabled the control of nucleation by visual observation. The parameters of crystal growth were determined. The crystal quality was estimated by X-ray diffraction method. The composition of crystals was determined by electron microprobe analysis and energy dispersive X-ray fluorescence analysis.

2

Type I CdSe and CdMgSe Quantum Wells

86%

Rudniewski R. , Rousset J. , Janik E. , Kossacki P. , Golnik A. , Nawrocki M. , Pacuski W.

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nr 5

1167-1170

EN

In this work we present the band gap engineering, epitaxial growth and optical characterization of CdSe/Cd_{0.9}Mg_{0.1}Se and Cd_{0.9}Mg_{0.1}Se/Cd_{0.85}Mg_{0.15}Se quantum wells with a thickness ranging from 1 to 15 nm. These structures exhibit strong near-band-gap photoluminescence from helium up to room temperature. The emission energy is tuned in the range from 1.74 to 2.1 eV at 7 K, depending on the thickness and well composition. The most intense photoluminescence (both at 7 and 300 K) was observed for 10 nm thick CdSe/Cd_{0.9}Mg_{0.1}Se wells. Such a structure gives also a sharp emission line (FWHM = 20 meV) at low temperature. The presented quantum wells are well suited for being embedded in lattice matched ZnTe based microcavities.

3

MBE Growth and Magnetooptical Properties of (Zn,Co)Te Layers

86%

Papaj M. , Kobak J. , Rousset J. , Janik E. , Golnik A. , Kossacki P. , Pacuski W.

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nr 6

1010-1011

EN

We report on epitaxial growth of diluted magnetic semiconductor (Zn,Co)Te. Reflectivity spectra reveal excitonic transition which split under magnetic field due to giant Zeeman effect. Magnetooptical effects can be described using literature data.

4

Temperature Dependence of Raman Scattering by Magnons in Bulk-Like MBE-Gwn MnTe Films

72%

Szuszkiewicz W. , Mohrange J. , Jouanne M. , Kanehisa M. , Świrkowicz R. , Dynowska E. , Janik E. , Wojtowicz T. , Kossut J.

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nr 5

1025-1028

EN

Temperature dependence of the magnon frequency was studied for cubic MnTe epilayers by the Raman scattering measurements. Experimental data are compared to the results of theoretical calculations performed within the framework of the Heisenberg model using Green's function formalism.

5

MBE Growth of CdTe/ZnTe Quantum Dots with Single Mn Ions

72%

Gietka K. , Kobak J. , Rousset J. , Janik E. , Słupiński T. , Kossacki P. , Golnik A. , Pacuski W.

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nr 6

1056-1058

EN

We report MBE growth and properties of samples with self assembled quantum dots with single manganese ions and low density of quantum dots. Manganese concentration was calibrated using magneto-reflectivity measurements and the giant Zeeman effect in (Cd,Mn)Te and (Zn,Mn)Te layers. Successful incorporation of Mn in the CdTe/ZnTe quantum dots was confirmed using micro-photoluminescence measurements: single manganese ion in quantum dot manifests in sixfold splitting of exciton emission lines due to s, p-d exchange interaction.

6

Half-Parabolic Quantum Wells of Diluted Magnetic Semiconductor Cd_{1-x}Mn_{x}Te

58%

Kutrowski M. , Wojtowicz T. , Cywiński G. , Karczewski G. , Janik E. , Dynowska E. , Kossut J. , Kossacki P. , Fiederling R. , Pfeuffer-Jeschke A. , Ossau W.

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nr 5

887-890

EN

We report on magnetooptical studies of MBE-grown half-parabolic CdTe/Cd_{x}Mn_{1-x}Te quantum well structures. The value of the valence band offset Q_{v}=0.4 ± 0.05 was determined by comparing energies of optical transitions in the absence of a magnetic field with model calculations. This value was verified by fitting the observed spin splitting of the lowest heavy hole (hh) state. We discuss also the temperature dependence of Q_{v}.

7

Photoluminescence Properties of ZnO Nanowires Grown on Ni Substrate

58%

Zaleszczyk W. , Fronc K. , Przeździecka E. , Janik E. , Czapkiewicz M. , Wróbel J. , Paszkowicz W. , Kłopotowski Ł. , Karczewski G. , Wojtowicz T. , Presz A.

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nr 5

1451-1456

EN

Photoluminescence studies of zinc oxide nanowires produced by a carbo-thermal method on a nickel foil substrate are reported. Two types of as-grown samples: the first - containing only buffer film, and the second - containing both zinc oxide nanowires and buffer film grown in the same technological process, were investigated by means of the temperature-dependent photoluminescence. X-ray diffraction measurements of buffer film show that it is polycrystalline and is composed from wurtzite-type ZnO (main phase) and includes minority phases: rock salt type (Ni,Zn)O and hexagonal C₃N₄. The shape of the apparently monocrystalline nanowires is characterized by hexagonal section matching with the expectations of the hexagonal ZnO structure. The presence of LO-phonon replicas in photoluminescence spectra for the second sample is used as an argument for confirmation that ZnO nanowires are single crystalline. The method of growth of ZnO nanowires on nickel oxide opens perspectives to produce Zn_{1-x}Ni_{x}O diluted magnetic semiconductor nanowires.

8

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

58%

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.

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nr 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.

9

Growth and Properties of ZnMnTe Nanowires

51%

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.

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nr 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.