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Sinito C, Corfdir P, Pfüller C, Gao G, Bartolomé J, Kölling S, Doblado AR, Jahn U, Lähnemann J, Auzelle T, Zettler JK, Flissikowski T, Koenraad P, Grahn HT, Geelhaar L, Fernández-Garrido S, Brandt O. Correction to Absence of Quantum-Confined Stark Effect in GaN Quantum Disks Embedded in (Al,Ga)N Nanowires Grown by Molecular Beam Epitaxy. Nano Lett 2020; 20:6930. [PMID: 32794760 DOI: 10.1021/acs.nanolett.0c02938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
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Sinito C, Corfdir P, Pfüller C, Gao G, Bartolomé J, Kölling S, Rodil Doblado A, Jahn U, Lähnemann J, Auzelle T, Zettler JK, Flissikowski T, Koenraad P, Grahn HT, Geelhaar L, Fernández-Garrido S, Brandt O. Absence of Quantum-Confined Stark Effect in GaN Quantum Disks Embedded in (Al,Ga)N Nanowires Grown by Molecular Beam Epitaxy. Nano Lett 2019; 19:5938-5948. [PMID: 31385709 DOI: 10.1021/acs.nanolett.9b01521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Several of the key issues of planar (Al,Ga)N-based deep-ultraviolet light-emitting diodes could potentially be overcome by utilizing nanowire heterostructures, exhibiting high structural perfection, and improved light extraction. Here, we study the spontaneous emission of GaN/(Al,Ga)N nanowire ensembles grown on Si(111) by plasma-assisted molecular beam epitaxy. The nanowires contain single GaN quantum disks embedded in long (Al,Ga)N nanowire segments essential for efficient light extraction. These quantum disks are found to exhibit intense light emission at unexpectedly high energies, namely, significantly above the GaN bandgap, and almost independent of the disk thickness. An in-depth investigation of the actual structure and composition of the nanowires reveals a spontaneously formed Al gradient both along and across the nanowire, resulting in a complex core/shell structure with an Al-deficient core and an Al-rich shell with continuously varying Al content along the entire length of the (Al,Ga)N segment. This compositional change along the nanowire growth axis induces a polarization doping of the shell that results in a degenerate electron gas in the disk, thus screening the built-in electric fields. The high carrier density not only results in the unexpectedly high transition energies but also in radiative lifetimes depending only weakly on temperature, leading to a comparatively high internal quantum efficiency of the GaN quantum disks up to room temperature.
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Affiliation(s)
- C Sinito
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - P Corfdir
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - C Pfüller
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - G Gao
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - J Bartolomé
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - S Kölling
- Department of Applied Physics , TU Eindhoven , Den Dolech 2 , 5612 Eindhoven , AZ , The Netherlands
| | - A Rodil Doblado
- Department of Applied Physics , TU Eindhoven , Den Dolech 2 , 5612 Eindhoven , AZ , The Netherlands
| | - U Jahn
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - J Lähnemann
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - T Auzelle
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - J K Zettler
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - T Flissikowski
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - P Koenraad
- Department of Applied Physics , TU Eindhoven , Den Dolech 2 , 5612 Eindhoven , AZ , The Netherlands
| | - H T Grahn
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - L Geelhaar
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - S Fernández-Garrido
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - O Brandt
- Paul Drude Institut für Festkörperelektronik , Leibniz Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
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Lähnemann J, Hill MO, Herranz J, Marquardt O, Gao G, Al Hassan A, Davtyan A, Hruszkewycz SO, Holt MV, Huang C, Calvo-Almazán I, Jahn U, Pietsch U, Lauhon LJ, Geelhaar L. Correlated Nanoscale Analysis of the Emission from Wurtzite versus Zincblende (In,Ga)As/GaAs Nanowire Core-Shell Quantum Wells. Nano Lett 2019; 19:4448-4457. [PMID: 31141672 DOI: 10.1021/acs.nanolett.9b01241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
While the properties of wurtzite GaAs have been extensively studied during the past decade, little is known about the influence of the crystal polytype on ternary (In,Ga)As quantum well structures. We address this question with a unique combination of correlated, spatially resolved measurement techniques on core-shell nanowires that contain extended segments of both the zincblende and wurtzite polytypes. Cathodoluminescence hyperspectral imaging reveals a blue-shift of the quantum well emission energy by 75 ± 15 meV in the wurtzite polytype segment. Nanoprobe X-ray diffraction and atom probe tomography enable k·p calculations for the specific sample geometry to reveal two comparable contributions to this shift. First, there is a 30% drop in In mole fraction going from the zincblende to the wurtzite segment. Second, the quantum well is under compressive strain, which has a much stronger impact on the hole ground state in the wurtzite than in the zincblende segment. Our results highlight the role of the crystal structure in tuning the emission of (In,Ga)As quantum wells and pave the way to exploit the possibilities of three-dimensional band gap engineering in core-shell nanowire heterostructures. At the same time, we have demonstrated an advanced characterization toolkit for the investigation of semiconductor nanostructures.
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Affiliation(s)
- Jonas Lähnemann
- Paul-Drude-Institut für Festkörperelektronik , Leibniz-Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - Megan O Hill
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Jesús Herranz
- Paul-Drude-Institut für Festkörperelektronik , Leibniz-Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - Oliver Marquardt
- Weierstraß-Institut für Angewandte Analysis und Stochastik , Leibniz-Institut im Forschungsverbund Berlin e.V. , Mohrenstr. 39 , 10117 Berlin , Germany
| | - Guanhui Gao
- Paul-Drude-Institut für Festkörperelektronik , Leibniz-Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - Ali Al Hassan
- Naturwissenschaftlich-Technische Fakultät der Universität Siegen , 57068 Siegen , Germany
| | - Arman Davtyan
- Naturwissenschaftlich-Technische Fakultät der Universität Siegen , 57068 Siegen , Germany
| | - Stephan O Hruszkewycz
- Materials Science Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Martin V Holt
- Center for Nanoscale Materials , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Chunyi Huang
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Irene Calvo-Almazán
- Materials Science Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik , Leibniz-Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
| | - Ullrich Pietsch
- Naturwissenschaftlich-Technische Fakultät der Universität Siegen , 57068 Siegen , Germany
| | - Lincoln J Lauhon
- Department of Materials Science and Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Lutz Geelhaar
- Paul-Drude-Institut für Festkörperelektronik , Leibniz-Institut im Forschungsverbund Berlin e.V. , Hausvogteiplatz 5-7 , 10117 Berlin , Germany
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Takagaki Y, Ramsteiner M, Jahn U, Jenichen B. Constituent substitution in hot wall deposition of Bi2S3 films by reaction with substrates. J SOLID STATE CHEM 2019. [DOI: 10.1016/j.jssc.2018.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Corfdir P, Marquardt O, Lewis RB, Sinito C, Ramsteiner M, Trampert A, Jahn U, Geelhaar L, Brandt O, Fomin VM. Excitonic Aharonov-Bohm Oscillations in Core-Shell Nanowires. Adv Mater 2019; 31:e1805645. [PMID: 30461088 DOI: 10.1002/adma.201805645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/15/2018] [Indexed: 06/09/2023]
Abstract
Phase coherence in nanostructures is at the heart of a wide range of quantum effects such as Josephson oscillations between exciton-polariton condensates in microcavities, conductance quantization in 1D ballistic transport, or the optical (excitonic) Aharonov-Bohm effect in semiconductor quantum rings. These effects only occur in structures of the highest perfection. The 2D semiconductor heterostructures required for the observation of Aharonov-Bohm oscillations have proved to be particularly demanding, since interface roughness or alloy fluctuations cause a loss of the spatial phase coherence of excitons, and ultimately induce exciton localization. Experimental work in this field has so far relied on either self-assembled ring structures with very limited control of shape and dimension or on lithographically defined nanorings that suffer from the detrimental effects of free surfaces. Here, it is demonstrated that nanowires are an ideal platform for studies of the Aharonov-Bohm effect of neutral and charged excitons, as they facilitate the controlled fabrication of nearly ideal quantum rings by combining all-binary radial heterostructures with axial crystal-phase quantum structures. Thanks to the atomically flat interfaces and the absence of alloy disorder, excitonic phase coherence is preserved even in rings with circumferences as large as 200 nm.
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Affiliation(s)
- Pierre Corfdir
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Oliver Marquardt
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
- Weierstraß-Institut für Angewandte Analysis und Stochastik, Leibniz-Institut im Forschungsverbund Berlin e. V., Mohrenstraße 39, 10117, Berlin, Germany
| | - Ryan B Lewis
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Chiara Sinito
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Manfred Ramsteiner
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Achim Trampert
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Lutz Geelhaar
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Oliver Brandt
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany
| | - Vladimir M Fomin
- Institute for Integrative Nanosciences, Leibniz IFW Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
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Abstract
Bi2Te3 is deposited by hot wall epitaxy in an attempt to form nanosheets on epitaxially-grown ferromagnetic layers of Fe, Fe3Si and Co2FeSi.
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Affiliation(s)
- Yukihiko Takagaki
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Jens Herfort
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Manfred Ramsteiner
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Bernd Jenichen
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
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Lin WH, Jahn U, Küpers H, Luna E, Lewis RB, Geelhaar L, Brandt O. Efficient methodology to correlate structural with optical properties of GaAs nanowires based on scanning electron microscopy. Nanotechnology 2017; 28:415703. [PMID: 28767046 DOI: 10.1088/1361-6528/aa8394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Twin boundaries and boundaries between zincblende (ZB) and wurtzite (WZ) segments of GaAs-related nanowires (NWs) form intrinsic heterointerfaces with essential consequences for the application of such nanomaterials in optoelectronic devices. We show that for GaAs and GaAs/(Al, Ga)As core/shell NWs, crystal twinning along the NW axis can be imaged with a spatial resolution of 10 nm using secondary electrons in a scanning electron microscope (SEM). Changes of the crystal structure from the ZB to the WZ phase have been investigated by electron backscatter diffraction. In addition to these methods, we employ spectrally and spatially resolved cathodoluminescence measurements in the same SEM to study the correlation between the structural and optical properties in single NWs. Two GaAs/AlAs/GaAs core/shell/shell NWs differing significantly in the crystal structure along their axis have been investigated combining these three techniques in order to demonstrate the strength of the employed methodology. Our experiments show that based on commonly available SEM methods, an overview of the structural properties along an entire NW and their impact on the spectral and spatial luminescence distribution can be efficiently obtained providing a quick feedback for the optimization of growth conditions.
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Affiliation(s)
- Wan-Hsien Lin
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, D-10117 Berlin, Germany
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Lewis RB, Corfdir P, Herranz J, Küpers H, Jahn U, Brandt O, Geelhaar L. Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant. Nano Lett 2017; 17:4255-4260. [PMID: 28654278 DOI: 10.1021/acs.nanolett.7b01185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Surface energies play a dominant role in the self-assembly of three-dimensional (3D) nanostructures. In this Letter, we show that using surfactants to modify surface energies can provide a means to externally control nanostructure self-assembly, enabling the synthesis of novel hierarchical nanostructures. We explore Bi as a surfactant in the growth of InAs on the {11̅0} sidewall facets of GaAs nanowires. The presence of surface Bi induces the formation of InAs 3D islands by a process resembling the Stranski-Krastanov mechanism, which does not occur in the absence of Bi on these surfaces. The InAs 3D islands nucleate at the corners of the {11̅0} facets above a critical shell thickness and then elongate along ⟨110⟩ directions in the plane of the nanowire sidewalls. Exploiting this growth mechanism, we realize a series of novel hierarchical nanostructures, ranging from InAs quantum dots on single {11̅0} nanowire facets to zigzag-shaped nanorings completely encircling nanowire cores. Photoluminescence spectroscopy and cathodoluminescence spectral line scans reveal that small surfactant-induced InAs 3D islands behave as optically active quantum dots. This work illustrates how surfactants can provide an unprecedented level of external control over nanostructure self-assembly.
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Affiliation(s)
- Ryan B Lewis
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Pierre Corfdir
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Jesús Herranz
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Hanno Küpers
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Oliver Brandt
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Lutz Geelhaar
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
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Lähnemann J, Flissikowski T, Wölz M, Geelhaar L, Grahn HT, Brandt O, Jahn U. Quenching of the luminescence intensity of GaN nanowires under electron beam exposure: impact of C adsorption on the exciton lifetime. Nanotechnology 2016; 27:455706. [PMID: 27713184 DOI: 10.1088/0957-4484/27/45/455706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electron irradiation of GaN nanowires in a scanning electron microscope strongly reduces their luminous efficiency as shown by cathodoluminescence imaging and spectroscopy. We demonstrate that this luminescence quenching originates from a combination of charge trapping at already existing surface states and the formation of new surface states induced by the adsorption of C on the nanowire sidewalls. The interplay of these effects leads to a complex temporal evolution of the quenching, which strongly depends on the incident electron dose per area. Time-resolved photoluminescence measurements on electron-irradiated samples reveal that the carbonaceous adlayer affects both the nonradiative and the radiative recombination dynamics.
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Zettler JK, Corfdir P, Hauswald C, Luna E, Jahn U, Flissikowski T, Schmidt E, Ronning C, Trampert A, Geelhaar L, Grahn HT, Brandt O, Fernández-Garrido S. Observation of Dielectrically Confined Excitons in Ultrathin GaN Nanowires up to Room Temperature. Nano Lett 2016; 16:973-980. [PMID: 26675526 DOI: 10.1021/acs.nanolett.5b03931] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The realization of semiconductor structures with stable excitons at room temperature is crucial for the development of excitonics and polaritonics. Quantum confinement has commonly been employed for enhancing excitonic effects in semiconductor heterostructures. Dielectric confinement, which gives rises to much stronger enhancement, has proven to be more difficult to achieve because of the rapid nonradiative surface/interface recombination in hybrid dielectric-semiconductor structures. Here, we demonstrate intense excitonic emission from bare GaN nanowires with diameters down to 6 nm. The large dielectric mismatch between the nanowires and vacuum greatly enhances the Coulomb interaction, with the thinnest nanowires showing the strongest dielectric confinement and the highest radiative efficiency at room temperature. In situ monitoring of the fabrication of these structures allows one to accurately control the degree of dielectric enhancement. These ultrathin nanowires may constitute the basis for the fabrication of advanced low-dimensional structures with an unprecedented degree of confinement.
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Affiliation(s)
- Johannes K Zettler
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Pierre Corfdir
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Christian Hauswald
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Esperanza Luna
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Timur Flissikowski
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Emanuel Schmidt
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1, 07743 Jena, Germany
| | - Carsten Ronning
- Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena , Max-Wien-Platz 1, 07743 Jena, Germany
| | - Achim Trampert
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Lutz Geelhaar
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Holger T Grahn
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Oliver Brandt
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
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Abstract
GaAs/GaAsBi coaxial multishell nanowires were grown by molecular beam epitaxy. Introducing Bi results in a characteristic nanowire surface morphology with strong roughening. Elemental mappings clearly show the formation of the GaAsBi shell with inhomogeneous Bi distributions within the layer surrounded by the outermost GaAs, having a strong structural disorder at the wire surface. The nanowire exhibits a predominantly ZB structure from the bottom to the middle part. The polytipic WZ structure creates denser twin defects in the upper part than in the bottom and middle parts of the nanowire. We observe room temperature cathodoluminescence from the GaAsBi nanowires with a broad spectral line shape between 1.1 and 1.5 eV, accompanied by multiple peaks. A distinct energy peak at 1.24 eV agrees well with the energy of the reduced GaAsBi alloy band gap by the introduction of 2% Bi. The existence of localized states energetically and spatially dispersed throughout the NW are indicated from the low temperature cathodoluminescence spectra and images, resulting in the observed luminescence spectra characterized by large line widths at low temperatures as well as by the appearance of multiple peaks at high temperatures and for high excitation powers.
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Affiliation(s)
- Fumitaro Ishikawa
- Graduate School of Science and Engineering, Ehime University , 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Yoshihiko Akamatsu
- Graduate School of Science and Engineering, Ehime University , 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Kentaro Watanabe
- WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Fumihiko Uesugi
- Transmission Electron Microscopy Station, National Institute for Materials Science , 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Shunsuke Asahina
- SM Business Unit, JEOL Ltd. , 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Satoshi Shimomura
- Graduate School of Science and Engineering, Ehime University , 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
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Zhang JP, Zhao JJ, Su XJ, Jahn U, Ji Y, Sun MS, Qiu YX, Liu XH, Huang J, Zhang JC, Xu K. B23-O-11Identification of Σ-Twinning in HVPE-AIN Single Crystals. Microscopy (Oxf) 2015. [DOI: 10.1093/jmicro/dfv170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Albert S, Bengoechea-Encabo AM, Barbagini F, Lopez-Rormero D, Sanchez-Garcia MA, Calleja E, Lefebvre P, Kong X, Jahn U, Trampert A, Müller M, Bertram F, Schmidt G, Veit P, Petzold S, Christen J, De Mierry P, Zuñiga-Perez J. Advances in MBE Selective Area Growth of III-Nitride Nanostructures: From NanoLEDs to Pseudo Substrates. Frontiers in Electronics 2015. [DOI: 10.1142/9789814656917_0007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Steven Albert
- ISOM-Dept. Ing. Electronica, ETSIT, Univ. Politecnica, E-28040 Madrid, Spain
| | | | - Francesca Barbagini
- ISOM-Dept. Ing. Electronica, ETSIT, Univ. Politecnica, E-28040 Madrid, Spain
| | - David Lopez-Rormero
- ISOM-Dept. Ing. Electronica, ETSIT, Univ. Politecnica, E-28040 Madrid, Spain
| | | | - Enrique Calleja
- ISOM-Dept. Ing. Electronica, ETSIT, Univ. Politecnica, E-28040 Madrid, Spain
| | - Pierre Lefebvre
- ISOM-Dept. Ing. Electronica, ETSIT, Univ. Politecnica, E-28040 Madrid, Spain
- CNRS–Laboratoire Charles Coulomb (L2C), UMR5221, F-34095 Montpellier, France
| | - Xiang Kong
- Paul-Drude Institut, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Uwe Jahn
- Paul-Drude Institut, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Achim Trampert
- Paul-Drude Institut, Hausvogteiplatz 5-7, 10117 Berlin, Germany
| | - Marcus Müller
- Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Frank Bertram
- Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Gordon Schmidt
- Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Peter Veit
- Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Silke Petzold
- Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Jürgen Christen
- Otto-von-Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
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14
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Sánchez-García MA, Sánchez FJ, Naranjo FB, Calle F, Calleja E, Muñoz E, Jahn U, Ploog KH. Crystal Morphology and Optical Emissions of GaN layers grown on Si(111) substrates by Molecular Beam Epitaxy. ACTA ACUST UNITED AC 2014. [DOI: 10.1557/s1092578300001046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Crystal morphology of GaN layers grown on Si(111) evolves from whisker-like microcrystals to compact films as a function of the III/V ratio. Small changes in the III/V ratio (from Ga-rich to N-rich) during the growth of a compact layer result in the appearance of microcrystals on the top of the layer, indicating a sharp transition between the two growth regimes.Four different morphologies are obtained by increasing the III/V ratio: a) completely columnar whisker-like samples exhibiting a pair of intense excitonic emissions at 3.471−3.478 eV; b) a mixture of compact regions with columnar microcrystals showing two pairs of excitonic emissionsnbsp c) compact layers with very small microcrystals on the top surface with a weaker dominant transition at 3.415 eV (±5meV) and, d) full compact and smooth layers with a single dominant excitonic emission at 3.466 eV. A combination of PL measurements with SEM photographs and CL imaging reveals that both pairs of emissions in samples b) come from the columnar microcrystals. The high energy pair (3.471−3.478eV) is attributed to the free-exciton A and a donor-bound exciton while the low energy pair (3.452−3.458eV) is assigned to acceptor-bound excitons associated to valence bands Γ9v and Γ7uv. Power and temperature dependence together with time-resolved data show that the dominant peak at 3.415eV (± 5meV) present in samples c) correspond to a donor-acceptor transition. CL measurements as a function of electron beam energy (depth) also indicate that this emission is more intense towards the interface between the layer and the sample. Finally, the excitonic emission in samples d) is shifted to lower energies due to residual biaxial tensile strain of thermal origin.
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15
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Dimakis E, Jahn U, Ramsteiner M, Tahraoui A, Grandal J, Kong X, Marquardt O, Trampert A, Riechert H, Geelhaar L. Coaxial multishell (In,Ga)As/GaAs nanowires for near-infrared emission on Si substrates. Nano Lett 2014; 14:2604-2609. [PMID: 24678901 DOI: 10.1021/nl500428v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Efficient infrared light emitters integrated on the mature Si technology platform could lead to on-chip optical interconnects as deemed necessary for future generations of ultrafast processors as well as to nanoanalytical functionality. Toward this goal, we demonstrate the use of GaAs-based nanowires as building blocks for the emission of light with micrometer wavelength that are monolithically integrated on Si substrates. Free-standing (In,Ga)As/GaAs coaxial multishell nanowires were grown catalyst-free on Si(111) by molecular beam epitaxy. The emission properties of single radial quantum wells were studied by cathodoluminescence spectroscopy and correlated with the growth kinetics. Controlling the surface diffusivity of In adatoms along the NW side-walls, we improved the spatial homogeneity of the chemical composition along the nanowire axis and thus obtained a narrow emission spectrum. Finally, we fabricated a light-emitting diode consisting of approximately 10(5) nanowires contacted in parallel through the Si substrate. Room-temperature electroluminescence at 985 nm was demonstrated, proving the great potential of this technology.
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Affiliation(s)
- Emmanouil Dimakis
- Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany
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16
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Takagaki Y, Jahn U, Giussani A, Calarco R. Multiple state transport deduced by weak antilocalization and electron-electron interaction effects in Sb(x)Te(1-x) layers. J Phys Condens Matter 2014; 26:095802. [PMID: 24525714 DOI: 10.1088/0953-8984/26/9/095802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Quantum corrections to the conductivity due to the weak antilocalization (WAL) and electron-electron interaction (EEI) effects are investigated in Sb-Te layers to evaluate the number of independent conduction channels in the topological insulator system. We separate the two contributions in the logarithmic temperature dependence of conductivity relying on their distinct response to a magnetic field. For the WAL effect, the amplitude parameter α being -1 observed in magnetoconductivity is confirmed. The magnitude of the EEI contribution is too large to be produced by one transport channel. The mixing between the surface and bulk states is thus indicated to be weak in the Sb-Te system. In addition, the disorder scattering appears to be less influential for the EEI effect than for the WAL effect.
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Affiliation(s)
- Y Takagaki
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin, Germany
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17
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Budach V, Becker ET, Boehmer D, Badakhshi H, Jahn U, Wernecke KD, Stromberger C. Concurrent hyperfractionated accelerated radiotherapy with 5-FU and once weekly cisplatin in locally advanced head and neck cancer. Strahlenther Onkol 2013; 190:250-5. [DOI: 10.1007/s00066-013-0481-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 09/26/2013] [Indexed: 12/01/2022]
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18
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Takagaki Y, Giussani A, Tominaga J, Jahn U, Calarco R. Transport properties in a Sb-Te binary topological-insulator system. J Phys Condens Matter 2013; 25:345801. [PMID: 23883483 DOI: 10.1088/0953-8984/25/34/345801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Sb-Te layers having various compositions between Sb2Te3 and Sb2Te are grown using molecular beam epitaxy. The structural and electrical properties of the layers change gradually with composition but exhibit a discontinuity involving a bistability. The holes in the layers are generated by Sb bilayers intercalated between Sb2Te3 quintuple layers and their mobility is governed by the scattering from the parent acceptors. Magnetoresistance for compositions around SbTe is linear, for which the reduction of the parabolic component due to low mobility is crucial. Density functional calculations predict Sb2Te3 and SbTe to be topological insulators (TIs) resembling Bi2Se3 and Bi2Te3, respectively. The prefactor of the weak antilocalization effect is α =- 1 regardless of the composition. The Sb-Te system is thus a family of TIs possessing undisturbed surface states for which the location of the Dirac point with respect to the bulk band gap is adjustable.
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Affiliation(s)
- Y Takagaki
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin, Germany.
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19
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Somaschini C, Bietti S, Trampert A, Jahn U, Hauswald C, Riechert H, Sanguinetti S, Geelhaar L. Control over the number density and diameter of GaAs nanowires on Si(111) mediated by droplet epitaxy. Nano Lett 2013; 13:3607-3613. [PMID: 23898953 DOI: 10.1021/nl401404w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present a novel approach for the growth of GaAs nanowires (NWs) with controllable number density and diameter, which consists of the combination between droplet epitaxy (DE) and self-assisted NW growth. In our method, GaAs islands are initially formed on Si(111) by DE and, subsequently, GaAs NWs are selectively grown on their top facet, which acts as a nucleation site. By DE, we can successfully tailor the number density and diameter of the template of initial GaAs islands and the same degree of control is transferred to the final GaAs NWs. We show how, by a suitable choice of V/III flux ratio, a single NW can be accommodated on top of each GaAs base island. By transmission electron microscopy, as well as cathodo- and photoluminescence spectroscopy, we confirmed the high structural and optical quality of GaAs NWs grown by our method. We believe that this combined approach can be more generally applied to the fabrication of different homo- or heteroepitaxial NWs, nucleated on the top of predefined islands obtained by DE.
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20
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Abstract
Foci of altered hepatocytes (FAH) including clear cell foci excessively storing glycogen (focal hepatic glycogenosis) are well known as preneoplastic lesions in animal models of hepatocarcinogenesis induced by chemical, physical or viral agents. The occurrence of similar lesions has been studied in a series of 67 explanted and 2 resected human livers using histological and histochemical approaches. A high incidence of FAH was found in the liver of patients suffering from hepatocellular carcinoma(HCC, 14/14) and liver cirrhosis (21/42). FAH were also detected in one patient each with inborn hepatic glycogenosis type 1a, and cholangiocellular carcinoma. Two patients with focal nodular hyperplasia had FAH-like enzymatic changes within these lesions. No FAH were found in 5 donor livers. FAH excessively storing glycogen including clear and mixed cell foci predominated in most cases with these lesions. The focal hepatic glycogenosis was associated with a significantly increased cell proliferation compared to the extrafocal parenchyma, and with alterations in the activity of various enzymes. In the 175 FAH studied by enzyme histochemistry, two enzymes involved in glycogen breakdown, namely glycogen phosphorylase and glucose-6-phosphatase, showed the most consistent changes, being reduced in 98% and 95%, respectively. In addition, the activities of adenosine triphosphatase and gamma-glutamyltransferase were reduced in 46% and 53% of FAH, respectively. Inconsistent changes were observed in FAH concerning a number of other enzymes. The 14 HCCs investigated histochemically often contained clear cell populations rich in glycogen in well differentiated portions, but were poor in glycogen in moderately and poorly differentiated tumors or tumor components. There were some similarities in the enzyme histochemical pattern of HCC and FAH but also important differences were evident. In contrast to FAH, all HCCs (except one carcinoma of the fibrolamellar type) showed an increase in the activity of the mitochondrial glycerol-3-phosphate dehydrogenase, and 50% of the cases had increased glucose-6-phosphate dehydrogenase activity. The activities of glucose-6-phosphatase and gamma-glutamyltransferase usually showed a reactivation, or even an increase compared to the extrafocal parenchyma, in moderately and poorly differentiated HCCs. Our results indicate that the focal hepatic glycogenosis is a putative preneoplastic lesion in human beings similar to laboratory animals. The focal hepatic glycogenosis appears to be a frequent initial step in neoplastic transformation of hepatocytes, a process associated with a fundamental shift in energy metabolism.
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Affiliation(s)
- P Bannasch
- UNIV HEIDELBERG, INST PATHOL, D-6900 HEIDELBERG, GERMANY. UNIV HANNOVER, DEPT SURG, HANNOVER, GERMANY. UNIV HEIDELBERG, DEPT SURG, D-6900 HEIDELBERG, GERMANY
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21
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Schubert T, Jahn U, Eben E, Deuber HJ. [Therapy for obesity--conservative and/or surgical?]. Gesundheitswesen 2013; 75:819-21. [PMID: 23468215 DOI: 10.1055/s-0033-1333741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
On comparing surgical and conservative approaches in therapy for obesity it is accepted that there is a more rapid decline in body weight after surgery than by conservative measures. In contrast to widespread convictions, it has been shown that even in extreme obesity (BMI>60 kg/m²) both a meaningful and a long-lasting reduction of body weight is possible by conservative approach. There is an increasing body of evidence that bariatric surgery, especially malabsorptive and combined forms, causes endocrine disturbances and both vitamin and micronutrient deficiencies. Furthermore, alterations in drug pharmacokinetics are possible. Even bariatric surgeons have stated that surgery neither removes the chronic disease obesity nor is its final therapy.
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Affiliation(s)
- Th Schubert
- Medizinischer Dienst der Krankenversicherung (MDK) Bayern
| | - U Jahn
- Medizinischer Dienst der Krankenversicherung (MDK) Bayern
| | - E Eben
- Medizinischer Dienst der Krankenversicherung (MDK) Bayern
| | - H J Deuber
- Medizinischer Dienst der Krankenversicherung (MDK) Bayern
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22
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Limbach F, Hauswald C, Lähnemann J, Wölz M, Brandt O, Trampert A, Hanke M, Jahn U, Calarco R, Geelhaar L, Riechert H. Current path in light emitting diodes based on nanowire ensembles. Nanotechnology 2012; 23:465301. [PMID: 23092897 DOI: 10.1088/0957-4484/23/46/465301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Light emitting diodes (LEDs) have been fabricated using ensembles of free-standing (In, Ga)N/GaN nanowires (NWs) grown on Si substrates in the self-induced growth mode by molecular beam epitaxy. Electron-beam-induced current analysis, cathodoluminescence as well as biased μ-photoluminescence spectroscopy, transmission electron microscopy, and electrical measurements indicate that the electroluminescence of such LEDs is governed by the differences in the individual current densities of the single-NW LEDs operated in parallel, i.e. by the inhomogeneity of the current path in the ensemble LED. In addition, the optoelectronic characterization leads to the conclusion that these NWs exhibit N-polarity and that the (In, Ga)N quantum well states in the NWs are subject to a non-vanishing quantum confined Stark effect.
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Affiliation(s)
- F Limbach
- Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin, Germany
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23
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Waag A, Wang X, Fündling S, Ledig J, Erenburg M, Neumann R, Al Suleiman M, Merzsch S, Wei J, Li S, Wehmann HH, Bergbauer W, Straßburg M, Trampert A, Jahn U, Riechert H. The nanorod approach: GaN NanoLEDs for solid state lighting. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/pssc.201000989] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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24
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Li S, Fündling S, Sökmen Ü, Neumann R, Merzsch S, Hinze P, Weimann T, Jahn U, Trampert A, Riechert H, Peiner E, Wehmann HH, Waag A. GaN nanorods and LED structures grown on patterned Si and AlN/Si substrates by selective area growth. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/pssc.200983457] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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25
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Li S, Fündling SÃ, Sökmen Ã, Merzsch S, Neumann R, Hinze P, Weimann T, Jahn U, Trampert A, Riechert H, Peiner E, Wehmann HH, Waag A. GaN and LED structures grown on pre-patterned silicon pillar arrays. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/pssc.200982608] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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26
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Fündling S, Sökmen U, Peiner E, Weimann T, Hinze P, Jahn U, Trampert A, Riechert H, Bakin A, Wehmann HH, Waag A. Gallium nitride heterostructures on 3D structured silicon. Nanotechnology 2008; 19:405301. [PMID: 21832611 DOI: 10.1088/0957-4484/19/40/405301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigated GaN-based heterostructures grown on three-dimensionally patterned Si(111) substrates by metal organic vapour phase epitaxy, with the goal of fabricating well controlled high quality, defect reduced GaN-based nanoLEDs. The high aspect ratios of such pillars minimize the influence of the lattice mismatched substrate and improve the material quality. In contrast to other approaches, we employed deep etched silicon substrates to achieve a controlled pillar growth. For that a special low temperature inductively coupled plasma etching process has been developed. InGaN/GaN multi-quantum-well structures have been incorporated into the pillars. We found a pronounced dependence of the morphology of the GaN structures on the size and pitch of the pillars. Spatially resolved optical properties of the structures are analysed by cathodoluminescence.
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Affiliation(s)
- Sönke Fündling
- Institut für Halbleitertechnik, Hans-Sommer-Straße 66, 38106 Braunschweig, Germany
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27
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Wang XL, Zhao DG, Jiang DS, Yang H, Liang JW, Jahn U, Ploog K. Al compositional inhomogeneity of AlGaN epilayer with a high Al composition grown by metal-organic chemical vapour deposition. J Phys Condens Matter 2007; 19:176005. [PMID: 21690942 DOI: 10.1088/0953-8984/19/17/176005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The Al compositional distribution of AlGaN is investigated by cathodoluminescence (CL). Monochromatic CL images and CL spectra reveal a lateral Al compositional inhomogeneity, which corresponds to surface hexagonal patterns. Cross-sectional CL images show a relatively uniform Al compositional distribution in the growth direction, indicating columnar growth mode of AlGaN films. In addition, a thin AlGaN layer with lower Al composition is grown on top of the buffer AlN layer near the bottom of the AlGaN epilayer because of the larger lateral mobility of Ga adatoms on the growth surface and their accumulation at the grain boundaries.
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Affiliation(s)
- X L Wang
- State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, Beijing 100083, People's Republic of China
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28
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Ristić J, Calleja E, Trampert A, Fernández-Garrido S, Rivera C, Jahn U, Ploog KH. Columnar AlGaN/GaN nanocavities with AlN/GaN Bragg reflectors grown by molecular beam epitaxy on Si(111). Phys Rev Lett 2005; 94:146102. [PMID: 15904080 DOI: 10.1103/physrevlett.94.146102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Indexed: 05/02/2023]
Abstract
Self-assembled columnar AlGaN/GaN nanocavities, with an active region of GaN quantum disks embedded in an AlGaN nanocolumn and cladded by top and bottom AlN/GaN Bragg mirrors, were grown. The nanocavity has no cracks or extended defects, due to the relaxation at the Si interface and to the nanocolumn free-surface to volume ratio. The emission from the active region matched the peak reflectivity by tuning the Al content and the GaN disks thickness. Quantum confinement effects that depend on both the disk thickness and the inhomogeneous strain distribution within the disks are clearly observed.
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Affiliation(s)
- Jelena Ristić
- ISOM and Departamento de Ingeniería Electrónica, Universidad Politécnica de Madrid, Madrid, Spain
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29
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Affiliation(s)
- U. Jahn
- Paul‐Drude‐Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin, Germany
| | - S. Dhar
- Paul‐Drude‐Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin, Germany
| | - H. Kostial
- Paul‐Drude‐Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin, Germany
| | - I. M. Watson
- University of Strathclyde, Glasgow G4 0NW, United Kingdom
| | - K. Fujiwara
- Kyushu Institute of Technology, Tobata, Kitakyushu 804‐8550, Japan
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Lucht M, Jahn U, Barnow S, Freyberger HJ. The use of a symptom checklist (SCL-90-R) as an easy method to estimate the relapse risk after alcoholism detoxification. Eur Addict Res 2002; 8:190-4. [PMID: 12457060 DOI: 10.1159/000066131] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We tested the use of some subscales of the psychiatric symptom checklist SCL-90-R in predicting relapse within a 1-year follow-up period after a combined detoxification- and abstinence-focused day patient psychotherapy program in 20 men and 13 women with alcohol dependence. Scores of the SCL-90-R subscales interpersonal sensitivity (p = 0.008), anxiety (p = 0.022), phobic anxiety (p = 0.019) and Global Severity Index (GSI; p = 0.040) on admission were higher in the subgroup with relapse within the first year after therapy. A decrease in depression (p = 0.004), anxiety (p = 0.006) and GSI (p = 0.006) scores during therapy was associated with a longer abstinence duration (shorter vs. longer than 24 weeks). Therefore we propose to further investigate the capacity of the SCL-90-R to identify subgroups at higher risk for relapse after detoxification and abstinence therapy in patients with alcohol dependence.
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Affiliation(s)
- M Lucht
- Department for Psychiatry and Psychotherapy, University of Greifswald, Stralsund, Germany.
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31
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32
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Jahn U. Tandem anionic Michael addition/radical cyclizations: a new and efficient strategy for the synthesis of functionalized cyclopentanes. Chem Commun (Camb) 2001:1600-1. [PMID: 12240401 DOI: 10.1039/b104415j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The combination of anionic Michael addition of lithium ester enolates with radical 5-exo cyclizations through SET oxidation gives highly functionalized cyclopentanes.
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Affiliation(s)
- U Jahn
- Institut für Organische Chemie, TU Braunschweig, Hagenring 30 D-38106, Braunschweig, Germany.
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Kleinoeder T, Jahn U, Rienhoff O. The need for evaluation when managing the IMIA.ORG web-site. Stud Health Technol Inform 2000; 68:543-6. [PMID: 10724947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The International Medical Informatics Association (IMIA) has built up a web-site to support international scientific exchange and facilitate organizational tasks. Regular monitoring is required to get information on whether the site is actually used and by whom. Main aspects of the evaluation are function, structure and contents. As main evaluation methods the logfile analysis and user questionnaires are used. The number of visits to IMIA's web-site has constantly increased in the last year. In January 1998 the site had 418 visits, in December 1998 there were 6002 visits. The user questionnaire showed that the web-site offers an adequate platform for the members. It is concluded that the members as the main target group are reached by the service and in addition that the growing number of non-members require further development of the public part of the site.
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Affiliation(s)
- T Kleinoeder
- Dept. of Nephrology & Rheumatology, University Hospital Goettingen, Germany
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Lohmann CH, Schwartz Z, Köster G, Jahn U, Buchhorn GH, MacDougall MJ, Casasola D, Liu Y, Sylvia VL, Dean DD, Boyan BD. Phagocytosis of wear debris by osteoblasts affects differentiation and local factor production in a manner dependent on particle composition. Biomaterials 2000; 21:551-61. [PMID: 10701456 DOI: 10.1016/s0142-9612(99)00211-2] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Wear debris is considered to be one of the main factors responsible for aseptic loosening of orthopaedic endoprostheses. Whereas the response of cells in the monocytic lineage to foreign materials has been extensively studied, little is known about cells at the bone formation site. In the present study, we examined the hypothesis that the response of osteoblasts to wear debris depends on the chemical composition of the particles. We produced particles from commercially pure titanium (cpTi), Ti-6Al-4V (Ti-A), and cobalt-chrome (CoCr) and obtained ultrahigh molecular weight polyethylene (UHMWPE; GUR 4150) particles from a commercial source. The equivalent circle diameters of the particles were comparable: 1.0 +/- 0.96 microm for UHMWPE; 0.84 +/- 0.12 microm for cpTi; 1.35 +/- 0.09 microm for Ti-A, and 1.21 +/- 0.16 microm for CoCr. Confluent primary human osteoblasts and MG63 osteoblast-like cells were incubated in the presence of particles for 24 h. Harvested cultures were examined by transmission electron microscopy to determine if the cells had phagocytosed the particles. Particles were found intracellularly, primarily in the cytosol, in both the primary osteoblasts and MG63 cells. The chemical composition of the particles inside the cells was confirmed by energy-dispersive X-ray analysis. Morphologically, both cell types had extensive ruffled cell membranes, less-developed endoplasmic reticulum, swollen mitochondria, and vacuolic inclusions compared with untreated cells. CpTi, Ti-A, and CoCr particles were also added to cultures of MG63 cells to assess their effect on proliferation (cell number) and differentiation (alkaline phosphatase activity), and PGE2 production. All three types of particles had effects on the cells. The effect on cell number was dependent on the chemical composition of the particles; Ti-A and CoCr caused a dose-dependent increase, while cpTi particles had a biphasic effect with a maximal increase in cell number observed at the 1:10 dilution. Alkaline phosphatase specific activity was also affected and cpTi was more inhibitory than Ti-A or CoCr. PGE2 production was increased by all particles, but the magnitude of the effect was particle-dependent: CoCr > cpTi > Ti-A. This study demonstrates clearly that human osteoblast-like cells and MG63 cells can phagocytose small UHMWPE, CoCr, Ti-A, and cpTi particles. Phagocytosis of the particles is correlated with changes in morphology, and analysis of MG63 response shows that cell proliferation, differentiation, and prostanoid production are affected. This may have negative effects on bone formation adjacent to an orthopaedic implant and may initiate or contribute to the cellular events that cause aseptic loosening by inhibiting bone formation. The effects on alkaline phosphatase and PGE2 release are dependent on the chemical composition of the particles, suggesting that both the type and concentration of wear debris at an implant site may be important in determining clinical outcome.
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Affiliation(s)
- C H Lohmann
- Department of Orthopaedics, University of Texas Health Science Center, San Antonio 78229-3900, USA
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Wurm RE, Cosgrove VP, Schlenger L, Kaiser A, Zeunert G, Dinges S, Bohsung J, Groll J, Pfaender M, Bauer S, Leonhardt G, Jahn U, Stuschke M, Budach V. Commissioning of a micro-multileaf collimator for conformal stereotactic radiosurgery and radiotherapy. Front Radiat Ther Oncol 1999; 33:64-77. [PMID: 10549477 DOI: 10.1159/000061247] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Affiliation(s)
- R E Wurm
- Klinik für Strahlentherapie, Charité, Humboldt University, Berlin, Germany.
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Schlenger L, Bohsung J, Cosgrove V, Groll J, Jahn U, Kaiser A, Pfaender M, Stuschke M, Budach V, Wurm R. Commissioning and clinical use of a micro multi-leaf collimator for conformal radiosurgery. Eur J Cancer 1999. [DOI: 10.1016/s0959-8049(99)80749-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Paradoxical air embolism may occur with any venous air embolism. Air may either enter the systemic circulation through a patent foramen ovale or through transpulmonary passage of air. While small venous air emboli are mostly well tolerated, even the smallest paradoxical air emboli can have fatal consequences in the systemic circulation. Therapy and prophylaxis of paradoxical air embolism equal those of venous air embolism. This is especially true, since paradoxical air embolism may not become obvious under general anesthesia. More specific therapeutic regiments, such as hyperbaric oxygenation and the infusion of perfluorocarbons, are still in an experimental stage.
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Affiliation(s)
- M Booke
- Klinik und Poliklinik für Anästhesie und operative Intensivmedizin, Westfälische Wilhelms-Universität, Münster
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Cosgrove VP, Jahn U, Pfaender M, Bauer S, Budach V, Wurm RE. Commissioning of a micro multi-leaf collimator and planning system for stereotactic radiosurgery. Radiother Oncol 1999; 50:325-36. [PMID: 10392819 DOI: 10.1016/s0167-8140(99)00020-1] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PURPOSE A computer controlled micro multi-leaf collimator, m3 mMLC, has been commissioned for conformal, fixed-field radiosurgery applications. Measurements were made to characterise the basic dosimetric properties of the m3, such as leaf transmission, leakage and beam penumbra. In addition, the geometric and dosimetric accuracy of the m3 was verified when used in conjunction with a BrainSCAN v3.5 stereotactic planning system. MATERIALS AND METHODS The m3 was detachably mounted to a Varian Clinac 2100C accelerator delivering 6 MV X-rays. Leaf transmission, leakage, penumbra and multiple, conformal fixed field dose distributions were measured using calibrated film in solid water. Beam data were collected using a diamond detector in a scanning water tank and planned dose distributions were verified using LiF TLDs and film. A small, shaped phantom was also constructed to confirm field shaping accuracy using portal images. RESULTS Mean transmission through the closed multi-leaves was 1.9 +/- 0.1% and leakage between leaves was 2.8 +/- 0.15%. Between opposing leaves abutting along the central beam-axis transmission was approximately 15 +/- 3%, but was reduced to a mean of 4.5 +/- 0.6% by moving the abutmen position 4.5 cm off-axis. Beam penumbrae were effectively constant as a function of increasing square field size and asymmetric fields and was seen to vary non-linearly when shaped to diagonal, straight edges. TMR, OAR and relative output beam data measurements of circular m3 fields were comparable to conventional, circular stereotactic collimators. Multiple, conformal field dose distributions were calculated with good spatial and dosimetric accuracy, with the planned 90% isodose curves agreeing with measurements to within 1-2 mm and to +/- 3% at isocentre. Portal films agreed with planned beams eye-view field shaping to within 1 mm. CONCLUSIONS The m3 micro multi-leaf collimator is a stable, high precision field-shaping device suitable for small-field, radiosurgery applications. Dose distributions can be accurately calculated by a planning system using only a few beam data parameters.
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Affiliation(s)
- V P Cosgrove
- Klinik für Strahlentherapie, Universitätsklinikum Charité, Berlin, Germany
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Jahn U, Kwok SH, Ramsteiner M, Hey R, Grahn HT, Runge E. Exciton localization, photoluminescence spectra, and interface roughness in thin quantum wells. Phys Rev B Condens Matter 1996; 54:2733-2738. [PMID: 9986125 DOI: 10.1103/physrevb.54.2733] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Menniger J, Jahn U, Brandt O, Yang H, Ploog K. Identification of optical transitions in cubic and hexagonal GaN by spatially resolved cathodoluminescence. Phys Rev B Condens Matter 1996; 53:1881-1885. [PMID: 9983646 DOI: 10.1103/physrevb.53.1881] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Abstract
From 1975-1994, 221 adult patients with a total of 232 radiation sites for soft tissue sarcomas were irradiated with fast neutrons with a mean energy of 6.2 MeV in Berlin-Buch/Dresden-Rossendorf. The tumour dose ranged between 6 and 12 Gy and was limited by the low dose penetration of the neutron beam. A local control rate of 66% was obtained. The local control was affected by the tumour differentiation, residual status and histological subtype. Severe fibrosis of the subcutaneous tissues occurred in 40% usually after 2 years. No serious general side effects occurred. To optimize neutron therapy, a high energy clinically-based cyclotron with a fully rotational gantry and a multileaf collimator should be utilized. It seems that patients with locally advanced and well differentiated sarcomas can benefit from this therapy.
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Affiliation(s)
- M Steingräber
- Virchow-Klinikum, Humboldt-Universität Berlin, Berlin-Buch, Germany
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Runge E, Menniger J, Jahn U, Hey R, Grahn HT. Roughness of heterointerfaces and averaging effects by excitons: Interpretation of cathodoluminescence images. Phys Rev B Condens Matter 1995; 52:12207-12211. [PMID: 9980365 DOI: 10.1103/physrevb.52.12207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Jahn U, Menniger J, Kwok SH, Runge E, Fujiwara K, Hey R, Grahn HT. Cathodoluminescence microscopy of inhomogeneities in semiconductor heterostructures. ACTA ACUST UNITED AC 1995. [DOI: 10.1002/pssa.2211500138] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Mennes WC, Wortelboer HM, Hassing GA, van Sandwijk K, Timmerman A, Schmid BP, Jahn U, Blaauboer BJ. Effects of clofibric and beclobric acid in rat and monkey hepatocyte primary culture: influence on peroxisomal and mitochondrial beta-oxidation and the activity of catalase, glutathione S-transferase and glutathione peroxidase. Arch Toxicol 1994; 68:506-11. [PMID: 7802591 DOI: 10.1007/s002040050103] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The effect of hypolipidaemic compounds on peroxisomal fatty acid beta-oxidation and on peroxisome morphology in the liver differs widely between rodent and primate species. We studied the relative importance of peroxisomal and mitochondrial beta-oxidation of palmitate in primary cultures of hepatocytes isolated from rat and monkey liver in the absence or presence of clofibric acid or beclobric acid. It was demonstrated that it is possible to differentiate between peroxisomal and mitochondrial beta-oxidation activities in intact cells. Overall beta-oxidation of palmitate was ca. 30% higher in rat hepatocytes than in monkey liver cells. In both monkey and rat cell cultures the mitochondrial component was over 90% of the total palmitate beta-oxidation. In rat hepatocyte culture clofibric acid and beclobric acid caused a 5- to 8-fold stimulation of peroxisomal beta-oxidation, while in monkey cells this activity was not significantly increased. However, in cells derived from both species mitochondrial palmitate beta-oxidation was increased (rat 2.5-fold; monkey 1.5-fold). These results indicate that the species differences in the increase in peroxisomal fatty acid oxidation are not a result of an inability to metabolize fatty acids in rat liver cell mitochondria. A comparison of the activity of enzymes involved in the detoxification of hydrogen peroxide showed that catalase and glutathione-S-transferase activity is 2.9-fold higher in monkey hepatocytes than in rat liver cells, while glutathione peroxidase activity was 1.6-fold higher in rat cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- W C Mennes
- Research Institute of Toxicology (RITOX), Utrecht University, The Netherlands
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Schmidt R, Rassow J, Haverkamp U, Hess A, Höver KH, Jahn U, Kronholz HL, Meissner P, Regel K. [The physical and technical outlook for neutron therapy in Germany]. Strahlenther Onkol 1993; 169:171-8. [PMID: 8465252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
All five fast neutron therapy centres in Germany use low energy cyclotrons or neutron generators and are, therefore, at the low energy end of the 21 neutron therapy facilities presently in use worldwide. The depth dose characteristics are worse than for 60Co gamma rays, the absorbed dose rate is too low and the treatment is technically restricted because of the lack of those modern features like multileaf collimators and full gantry rotation that are available with modern linear accelerators. A survey of the statistical and methodical data on the neutron treatment in Germany is presented. To avoid masking the potential biological benefits of high LET neutron irradiation by the use of suboptimal equipment and to utilise the real therapeutical benefit for specific tumor types, the German neutron therapy centres urgently need modernization of their outdated facilities. Specific recommendations of how to meet the requirements of modern neutron therapy are given.
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Affiliation(s)
- R Schmidt
- Abteilung Strahlentherapie, Universitätskrankenhaus Hamburg-Eppendorf
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Duschl A, Jahn U, Bertling C, Sebald W. A comparison of assays for the response of primary human T-cells upon stimulation with interleukin-2, interleukin-4 and interleukin-7. Eur Cytokine Netw 1992; 3:97-102. [PMID: 1586702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The most commonly used assay to quantitate the response of peripheral T-cells upon stimulation with growth factors is determination of incorporated [3H]TdR. We compared this test to three other methods: 1. direct counting of cells with a Coulter type counter as reference assay, 2. a colorimetric assay using the tetrazolium dye 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium (MTT), which is a cheap and increasingly popular non-radioactive method and 3. incorporation of the thymidine analog 5-bromo-2'-deoxyuridine detection with a monoclonal antibody on cytospins. Primary human PHA-blasts from greater than 30 healthy individuals were stimulated with IL-2, IL-4 and IL-7 and assayed with up to four different methods. We discuss the advantages and disadvantages of the assays used and the effects of differences between cell preparations. We observed no significant variations between individuals for the dose dependence, but the relative efficiency of IL-4 compared to IL-2 and IL-7 was variable. This was probably due to the slower response observed upon stimulation with this factor.
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Affiliation(s)
- A Duschl
- Theodor-Boveri-Institüt fur Biowissenschaften Universität Würzburg, FRG
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Kachel R, Jahn U, Schiffmann R, Basche S. [Complications in cerebral angiography. A study of 6698 cerebral angiographies]. Rev Med Chir Soc Med Nat Iasi 1991; 95:97-105. [PMID: 1823439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The complications of 6,698 cerebral angiographies performed from 1979 to 1985 in 2,503 patients were analysed. In 5.24% of the patients (1.95% of the angiopathies) temporary complications could be observed. Temporary neurologic-psychiatric complications occurred in 1.96% of the patients (0.73% of the angiographies), most of them in middle-aged patients and in the presence in the presence of diffuse cerebrovascular disease. In 0.12% of the patients (0.05% of the angiographies) a permanent damage was recorded.
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Affiliation(s)
- R Kachel
- Arbeitsbereich für kardiovaskuläre Röntgendiagnostik, Medizinische Akademie Erfurt
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Zirngibl L, Fischer J, Jahn U, Thiele K. Structure-activity relationships of 2-(1H-imidazol-1-yl)vinyl ethers. Route to the new broad-spectrum antifungal agent omoconazole. Ann N Y Acad Sci 1988; 544:63-73. [PMID: 3214095 DOI: 10.1111/j.1749-6632.1988.tb40389.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- L Zirngibl
- Research Department, Siegfried, Ltd., Zofingen, Switzerland
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Jahn U, Thiele K. In vitro inhibition of xanthine oxidase by azapropazone and 8-hydroxy-azapropazone. Arzneimittelforschung 1988; 38:507-8. [PMID: 3401265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
It has been demonstrated that the nonsteroidal antiinflammatory agent azapropazone (Prolixan) as well as its principal 8-hydroxy-metabolite have distinct xanthine oxidase inhibitory activity. The pharmacological spectrum of this compound has thus shown an interesting extension.
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Affiliation(s)
- U Jahn
- Biology and Research Department, Siegfried Ltd., Zofingen, Switzerland
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