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1

Morphology and Optical Properties of Laser-Assisted Chemical Vapour Deposited GaN

100%

Goldys E., Godlewski M., Tansley T.

Acta Physica Polonica A

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1998

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vol. 94

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issue 2

331-335

EN

Properties of GaN epilayers grown by laser-assisted chemical vapour deposition are discussed. Good crystallinity and surface morphology of the films is demonstrated. Micro-Raman spectra are explained by scattering by small, randomly oriented cubic phase units present in the GaN film.

2

Neutron Transmutation Doped GaP: Optically Detected Magnetic Resonance Studies

88%

Heijmink Liesert B., Godlewski M., Gregorkiewicz T., Ammerlaan C., Goldys E.

Acta Physica Polonica A

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1991

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vol. 79

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issue 2-3

401-404

EN

The first direct proof for successful neutron transmutation doping (NTD) of GaP is presented on the basis of optically detected magnetic resonance (ODMR). GaP:S samples grown by the liquid encapsulated Czochralski method were irradiated with thermal neutrons and subsequently annealed at 800°C. In the ODMR experiments the transmuted Ge substitutional on Ga sites was detected. The NTD process was also found to create deep acceptors, the nature of which will be tentatively discussed.

3

Structure, Surface Morphology and Optical Properties of Thin Films of ZnS and CdS Grown by Atomic Layer Epitaxy

76%

Szczerbakow A., Godlewski M., Dynowska E., Ivanov V., Świątek K., Goldys E., Phillips M.

Acta Physica Polonica A

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1998

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vol. 94

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issue 3

579-582

EN

In this communication we report successful growth of monocrystalline cubic ZnS and monocrystalline and polycrystalline cubic and wurtzite films of CdS by atomic layer epitaxy. Structural and optical properties of these films are analysed. ZnS (and CdS/ZnS) films grown on GaAs substrate are cubic. Atomic layer epitaxy grown films provide several advantages over ZnS and CdS materials grown by other techniques, especially compared to bulk material, which is grown at higher temperatures. First results for ZnS/CdS/ZnS quantum well structures are also discussed.

4

Growth and Characterization of ZnO Nanoparticles

76%

Tomaszewska-Grzęda A., Łojkowski W., Godlewski M., Yatsunenko S., Drozdowicz-Tomsia K., Goldys E., Phillips M.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

897-902

EN

In this work we evaluate structural and optical properties of ZnO nanoparticles grown by wet chemistry method. Light emission properties of these nanoparticles are studied with cathodoluminescence and micro-photoluminescence. Even at the room temperature excitonic emission is well resolved, due to high exciton binding energy of ZnO. Decay kinetics of photoluminescence emissions and efficiency of inter-nanoparticles energy migration is evaluated from maps of in-plane variations of photoluminescence decay times measured in microphotoluminescence setup.

5

Dynamics of Light Emission in CdMnS Nanoparticles

76%

Godlewski M., Yatsunenko S., Drozdowicz-Tomsia K., Goldys E., Phillips M., Klar P., Heimbrodt W.

Acta Physica Polonica A

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2005

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vol. 108

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issue 4

681-688

EN

We demonstrate coexistence of slow and fast components of photoluminescence decay of the Mn^{2+} intra-shell emission in nanoparticles of CdMnS. We explain the observed decrease in PL lifetime of the Mn^{2+} intra-shell transition by high efficiency of spin dependent magnetic interactions between localized spins of Mn^{2+} ions and free carriers. This mechanism is enhanced in nanostructures, but it is also present in bulk samples.

6

Origin of Ultrafast Component of Photoluminescence Decay in Nanostructures Doped with Transition Metal or Rare-Earth Ions

64%

Godlewski M., Yatsunenko S., Ivanov V., Khachapuridze A., Świątek K., Goldys E., Phillips M., Klar P., Heimbrodt W.

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EN

Bulk samples, layers, quantum well, and quantum dot structures of II-Mn-VI samples all show coexistence of slow and fast components of Mn^{2+} photoluminescence decay. Thus, fast photoluminescence decay cannot be related to low dimensionality of a host material. This also means that the model of the so-called quantum confined atom is incorrect. Based on the results of time-resolved photoluminescence and optically detected magnetic resonance investigations we relate the observed lifetime decrease in Mn^{2+} intra-shell transition to spin dependent magnetic interactions between localized spins of Mn^{2+} ions and between Mn^{2+} ions and spins/magnetic moments of free carriers. The latter mechanism is enhanced in nanostructures.

7

Mechanisms of Yellow and Red Photoluminescence in Wurtzite and Cubic GaN

64%

Godlewski M., Suski T., Grzegory I., Porowski S., Langer R., Barski A., Bergman J., Monemar B., Goldys E., Phillips M.

Acta Physica Polonica A

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1998

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vol. 94

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issue 2

326-330

EN

The origin of two "deep" photoluminescence (PL) emissions observed in wurtzite (yellow PL) and cubic (red PL) GaN is discussed. PL and time-resolved PL studies confirm donor-acceptor pair character of the yellow band in wurtzite GaN and point to participation of shallow donors in this emission. A similar PL mechanism is proposed for the red emission of cubic GaN. We further show a puzzling property of both yellow and red PLs. Both yellow and red emissions show spatial homogeneity and are only weakly dependent on surface morphology.

8

Cathodoluminescence Profiling of InGaN-Based Quantum Well Structures and Laser Diodes - In-Plane Instabilities of Light Emission

52%

Godlewski M., Ivanov V., Goldys E., Phillips M., Böttcher T., Figge S., Hommel D., Czernecki R., Prystawko P., Leszczynski M., Perlin P., Grzegory I., Porowski S.

Acta Physica Polonica A

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2003

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vol. 103

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issue 6

689-694

EN

Instabilities of light emission and also of stimulated emission in series of GaN epilayers and InGaN quantum well structures, including laser diode structures, are studied. A stimulated emission is observed under electron beam pumping. This enabled us to study light emission properties from laser structures and their relation to microstructure details. We demonstrate large in-plane fluctuations of light emission and that these fluctuations are also present for excitation densities larger than the threshold densities for the stimulated emission.

9

Relationship between Sample Morphology and Carrier Diffusion Length in GaN Thin Films

52%

Godlewski M., Goldys E., Phillips M., Böttcher T., Figge S., Hommel D., Czernecki R., Prystawko P., Leszczynski M., Perlin P., Wisniewski P., Suski T., Bockowski M., Grzegory I., Porowski S.

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issue 4-5

627-632

EN

Scanning and spot-mode cathodoluminescence investigations of homo- and hetero-epitaxial GaN films indicate a surprisingly small influence of their microstructure on overall intensity of a light emission. This we explain by a correlation between structural quality of these films and diffusion length of free carriers and excitons. Diffusion length increases with improving structural quality of the samples, which, in turn, enhances the rate of nonradiative recombination on structural defects, such as dislocations.

10

Spin Dependent Interactions of Free Carriers and Manganese Ions in Nanostructures of Wide Band Gap II-Mn-VI Semiconductors - Mechanism of Lifetime Reduction

52%

Yatsunenko S., Khachapuridze A., Ivanov V., Godlewski M., Khoi L., Gołacki Z., Karczewski G., Goldys E., Phillips M., Klar P., Heimbrodt W.

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EN

Based on the results of optically detected magnetic resonance and time-resolved investigations we relate the observed lifetime shortening of intra-shell Mn^{2+} emission to spin dependent magnetic interactions between localized spins of Mn^{2+} ions and spins/magnetic moments of free carriers. We show that this mechanism is active in both bulk and in low dimensional structures, such as quantum wells, quantum dots, and nanostructures.

Refine search results

Morphology and Optical Properties of Laser-Assisted Chemical Vapour Deposited GaN

Neutron Transmutation Doped GaP: Optically Detected Magnetic Resonance Studies

Structure, Surface Morphology and Optical Properties of Thin Films of ZnS and CdS Grown by Atomic Layer Epitaxy

Growth and Characterization of ZnO Nanoparticles

Dynamics of Light Emission in CdMnS Nanoparticles

Origin of Ultrafast Component of Photoluminescence Decay in Nanostructures Doped with Transition Metal or Rare-Earth Ions

Mechanisms of Yellow and Red Photoluminescence in Wurtzite and Cubic GaN

Cathodoluminescence Profiling of InGaN-Based Quantum Well Structures and Laser Diodes - In-Plane Instabilities of Light Emission

Relationship between Sample Morphology and Carrier Diffusion Length in GaN Thin Films

Spin Dependent Interactions of Free Carriers and Manganese Ions in Nanostructures of Wide Band Gap II-Mn-VI Semiconductors - Mechanism of Lifetime Reduction