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1
Content available remote Type I CdSe and CdMgSe Quantum Wells
100%
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.
2
Content available remote Numerical Rate Equation Approach to Picosecond Charge State Dynamics in CdTe/ZnTe Quantum Dots
100%
Koperski M. , Kazimierczuk T. , Goryca M. , Wojnar P. , Golnik A. , Kossacki P. , Gaj J.
Acta Physica Polonica A
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2009
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tom 116
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nr 5
893-895
EN
The rate equation is used for description of photoluminescence dynamics after pulsed excitation of various states of quantum dots. The picosecond dynamics of averaged charge state of quantum dot is described. We compare our simulations with the experiment and come up with the conclusion that probability of carrier capture weakly depends on quantum dot charge state and that electrons and holes are captured non-synchronously.
3
Content available remote Anisotropic Exchange Interaction between p-Shell Electron and s-Shell Hole in CdTe/ZnTe Quantum Dots
100%
Kazimierczuk T. , Golnik A. , Goryca M. , Wojnar P. , Gaj J. , Kossacki P.
Acta Physica Polonica A
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2009
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tom 116
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nr 5
882-884
EN
We study electron-hole exchange interaction in a single CdTe/ZnTe quantum dot by polarization-resolved photoluminescence measurements. We focus on recombination of excitonic states involving p-shell electrons: X^{2-} and XX^-. Recombination lines of X^{2-} and XX^- states exhibit fine structure, which can be consistently explained within a model with four parameters δ_{i}^{αβ} representing strength of iso- and anisotropic parts of interaction between s-hole and s- or p-electron.
4
Content available remote Control of Local Electric Fields Influencing the Photoluminescence οf an Individual CdTe/ZnTe Quantum Dot
100%
Haas K. , Kazimierczuk T. , Wojnar P. , Golnik A. , Gaj J. , Kossacki P.
Acta Physica Polonica A
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2009
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tom 116
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nr 5
896-898
EN
We examine the influence of a weak non-resonant illumination on the quantum dot photoluminescence spectrum. We observe that even very weak illumination affects both intensity and spectral position of emission lines in the spectrum. We discover no significant asymmetry in spatial dependence and infer that the observed effects cannot be attributed to a single neighbor center.
5
Content available remote Magnetization Dynamics of a (Cd,Mn)Te Quantum Well in Pulsed Magnetic Field
100%
Kobak J. , Goryca M. , Kossacki P. , Golnik A. , Karczewski G. , Wojtowicz T. , Gaj J.
Acta Physica Polonica A
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2009
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tom 116
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nr 5
907-908
EN
In this paper we present studies of magnetization relaxation in a (Cd,Mn)Te quantum well containing 3.2% of Mn, after a pulse of magnetic field. The relaxation was found to be very fast, with dominant component faster than 10 ns. Upon application of static magnetic field the relaxation does not slow down, in contrast with the behavior of very diluted quantum wells or bulk material.
6
Content available remote Cold and Hot Excitons in CdMnTe/CdMgTe Quantum Wells in Strong Excitation Regime and External Magnetic Field
100%
Trajnerowicz A. , Golnik A. , Kossacki P. , Bardyszewski W. , Wiater M. , Karczewski G. , Wojtowicz T.
Acta Physica Polonica A
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2009
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tom 116
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nr 5
849-851
EN
Systematic studies of neutral heavy-hole excitonic line energy changes in a strong excitation regime were carried out by means of a pump-probe method for quantum wells containing a 2D gas of free holes. Energy shift of X_{e1hh1} line was analyzed for different excitation energies at fixed delay between pump and probe pulses, also under external magnetic field. It was observed that this shift depends not only on the density of created excitons but also directly on the pump energy. In co-polarization configuration for excitation energy below an absorption resonance the energetic blue shift rises linearly with the elevated exciton density (localized excitons are created). For energies slightly above the resonance, the blue shift diminishes dramatically in spite of high exciton density present (delocalized excitons are created). Model absorption calculations are in qualitative agreement with the experimental data.
7
Content available remote MBE Growth and Magnetooptical Properties of (Zn,Co)Te Layers
100%
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.
8
Content available remote Inter-Dot Coupling in a Self-Assembled Quantum Dot System
100%
Kazimierczuk T. , Nowak S. , Suffczyński J. , Wojnar P. , Golnik A. , Gaj J. , Kossacki P.
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nr 2
321-324
EN
We present studies of resonant excitation of self-assembled CdTe/ZnTe quantum dots. Photoluminescence excitation measurements revealed existence of sharp resonances, common for photoluminescence lines attributed to different quantum dot charge states. We conclude from the ensemble of photoluminescence and photoluminescence excitation results that we observe energy transfer in coupled quantum dot pairs.
9
Content available Measurement of Very Small Zeeman Splittings in GaN:Mn,Mg by Faraday Rotation
84%
Wołoś A. , Kossacki P. , Golnik A. , Kamińska M. , Gaj J. , Twardowski A. , Grzegory I. , Boćkowski M. , Porowski S.
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nr 4-5
695-699
EN
In this work we demonstrate an application of Faraday rotation for measuring an extremely small Zeeman splitting of an Mn related absorption line placed at 1.417 eV in optical absorption spectrum of Mn and Mg doped gallium nitride. Analysis of the collected spectra allowed us to determine the value of the splitting as equal to 0.12±0.01 meV at 6 T. This data should help in establishing the nature of the observed absorption band.
10
Content available remote Optical Study of ZnTe-Based 2D and 0D Photonic Structures Containing CdTe/ZnTe Quantum Dots
84%
Jakubczyk T. , Kazimierczuk T. , Golnik A. , Bienias P. , Pacuski W. , Kruse C. , Hommel D. , Kłopotowski Ł. , Wojtowicz T. , Gaj J.
Acta Physica Polonica A
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2009
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tom 116
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nr 5
888-889
EN
We report on an optical study of ZnTe-based microcavity and micropillars. Angle-resolved reflectivity studies confirm a high quality of the investigated structure by setting the lower bound on the quality factor Q ≥ 1000, determined from normal-incidence reflection spectra. In a microphotoluminescence study, micropillar modes are observed at temperatures of the order of tens of kelvins. For structures grown by a complex growth procedure at two different MBE facilities, an enhancement of photoluminescence in the cavity mode is observed.
11
Content available remote Spin-Related Spectroscopy of CdTe-Based Quantum Dots
84%
Gaj J. , Kazimierczuk T. , Goryca M. , Koperski M. , Golnik A. , Kossacki P. , Nawrocki M. , Wojnar P. , Karczewski G.
Acta Physica Polonica A
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2009
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tom 116
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nr 5
795-799
EN
This work contains a selection of our recent experimental results in the field of the spin-related spectroscopy of individual CdTe-based quantum dots. After a short description of the sample growth and experimental methods, optical measurements of the charge state dynamics are presented. Then the influence of in-plane anisotropy of the excitonic states of a quantum dot is discussed, followed by a description of experimental studies of information read-out and writing on quantum dot spin states. In particular, spin memory of a single Mn^{++} ion embedded in a CdTe quantum dot is quantitatively assessed. In an outlook part, perspectives opened by recently developed ZnTe lattice-matched Bragg reflectors are discussed.
12
Content available remote MBE Growth of CdTe/ZnTe Quantum Dots with Single Mn Ions
84%
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.
13
Content available remote Optical Properties of CdTe QDs Formed Using Zn Induced Reorganization
84%
Kobak J. , Pacuski W. , Jakubczyk T. , Kazimierczuk T. , Golnik A. , Frank K. , Rosenauer A. , Kruse C. , Hommel D. , Gaj J.
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nr 5
627-629
EN
In this paper we present optical studies of CdTe quantum dots formed using Zn-induced reorganization. The pattern of quantum dot photoluminescence lines is found to be similar to typical results reported for quantum dots grown with other techniques, although the positively charged exciton line is relatively more pronounced. Also the energy spacing between biexciton and exciton lines is found to be larger than in typical results. Zn-induced reorganization results in quantum dots density higher by an order of magnitude than in Te-induced quantum dots.
14
Content available remote Excitation Mechanisms of CdTe/ZnTe Quantum Dots under Non-Resonant and Quasi-Resonant Regime
84%
Kazimierczuk T. , Gaj J. , Golnik A. , Goryca M. , Nawrocki M. , Koperski M. , Smoleński T. , Suffczyński J. , Wojnar P. , Kossacki P.
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nr 5
588-591
EN
We discuss possible mechanisms of quantum dot population control. A set of experiments, including time-resolved photoluminescence, single photon correlations, excitation correlation, and photoluminescence excitation is used to determine the actual mechanism under non-resonant and quasi-resonant regime.
15
Content available remote Growth and Properties of ZnMnTe Nanowires
59%
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.
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