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Your search keyword '"Ludvig de Knoop"' showing total 7 results
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7 results on '"Ludvig de Knoop"'

1. An STM – SEM setup for characterizing photon and electron induced effects in single photovoltaic nanowires

Author

Thomas Kanne, Lunjie Zeng, Jonatan Holmér, Eva Olsson, Jesper Nygård, Ludvig de Knoop, and Peter Krogstrup

Subjects
010302 applied physics, Materials science, Renewable Energy, Sustainability and the Environment, Scanning electron microscope, business.industry, Electron beam-induced current, Nanowire, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Electrical contacts, law.invention, Semiconductor, law, 0103 physical sciences, Optoelectronics, General Materials Science, Electrical and Electronic Engineering, Scanning tunneling microscope, 0210 nano-technology, business, Ohmic contact, Light-emitting diode
Abstract

Vertical arrays of semiconductor nanowires show great potential for material-efficient and high-performance solar cells. The characterization and correlation between material structure and properties of the individual nanowires are crucial for the continued performance improvement of such devices. In this work, we developed a method with a scanning tunneling microscope (STM) probe inside a scanning electron microscope (SEM) to enable the studies of single photovoltaic nanowires. The STM probe is used to contact individual nanowires in ensembles. We combine the STM-SEM with an in situ light emitting diode (LED) illumination source to study both the electrical and photovoltaic properties of vertical GaAs nanowires with radial p-i-n junctions. We also illustrate that the local charge separation ability within the nanowires can be studied by electron beam induced current (EBIC) measurements. The in situ SEM setup allows the correlation between properties and nanowire structure. The data show that the quality of the electrical contact to the semiconductor nanowire is crucial to be able to investigate the inherent properties of the nanowires. We have established a procedure to make high-quality ohmic contacts to the nanowires with the STM probe. We also show that the effect of mechanical strain on the electrical properties can be investigated by the STM-SEM setup.

Published
2018
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2. Localized resistance measurements of wrinkled reduced graphene oxide using in-situ transmission electron microscopy

Author

John Cumings, Eva Olsson, Ludvig de Knoop, and Hanna M. Nilsson

Subjects
Materials science, Chemistry(all), Oxide, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, law.invention, chemistry.chemical_compound, law, General Materials Science, Electrical measurements, Nanoscopic scale, business.industry, Graphene, Contact resistance, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, In situ transmission electron microscopy, chemistry, Transmission electron microscopy, Electrode, Optoelectronics, 0210 nano-technology, business
Abstract

The tunable electrical properties of reduced graphene oxide (rGO) make it an ideal candidate for many applications including energy storage. However, in order to utilize the material for applications it is essential to understand the behavior of the material on the nanoscale, especially how naturally occurring phenomena like wrinkling affect the electronic transport. Here, we use a transmission electron microscope (TEM) with electrical probe in-situ holder to perform localized electrical measurements on wrinkled, supported rGO flakes. The TEM allows for observation of the local wrinkled structure of the rGO and simultaneously an electrical probe is used to perform localized resistance measurements. For these measurements, there is no correlation between the electrode distance and the measured resistance indicating that contact resistance varies and dominates the measurements. There is, however, a correlation between increasing number of wrinkles underneath the probe and decreasing resistance, indicating that the wrinkles can provide surface area for contact with the probe and thus lower the resistance. The overall resistance is on the order of single kΩ, if the contact between the probe and the rGO is optimized. These measurements give evidence that rGO with wrinkling can compete as a leading type of graphene for certain applications.

Published
2017
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3. Electric-field-controlled reversible order-disorder switching of a metal tip surface

Author

Mattias Thuvander, Mikael Kuisma, Alexandre Dmitriev, Kristof Lodewijks, Ludvig de Knoop, Paul Erhart, Eva Olsson, and Joakim Löfgren

Subjects
Surface (mathematics), crystal structure, Materials science, Physics and Astronomy (miscellaneous), Nanophotonics, metals, FOS: Physical sciences, 02 engineering and technology, Physical Chemistry, 7. Clean energy, 01 natural sciences, Atomic units, law.invention, Metal, law, Electric field, 0103 physical sciences, Materials Chemistry, General Materials Science, metallit, 010306 general physics, ta116, roughness, Condensed Matter - Materials Science, ta114, Transistor, Materials Science (cond-mat.mtrl-sci), Decoupling (cosmology), Condensed Matter Physics, 021001 nanoscience & nanotechnology, phase transitions, Characterization (materials science), pintailmiöt, Chemical physics, sähkökentät, visual_art, visual_art.visual_art_medium, 0210 nano-technology
Abstract

While it is well established that elevated temperatures can induce surface roughening of metal surfaces, the effect of a high electric field on the atomic structure at ambient temperature has not been investigated in detail. Here we show with atomic resolution using in situ transmission electron microscopy how intense electric fields induce reversible switching between perfect crystalline and disordered phases of gold surfaces at room temperature. Ab initio molecular dynamics simulations reveal that the mechanism behind the structural change can be attributed to a vanishing energy cost in forming surface defects in high electric fields. Our results demonstrate how surface processes can be directly controlled at the atomic scale by an externally applied electric field, which promotes an effective decoupling of the topmost surface layers from the underlying bulk. This opens up opportunities for development of active nanodevices in e.g. nanophotonics and field-effect transistor technology as well as fundamental research in materials characterization and of yet unexplored dynamically-controlled low-dimensional phases of matter., Comment: The manuscript is 10 pages long and the supplemental material is 15 pages. There are six supplemental movies that can be provided upon request to LDK

Published
2018
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4. In Situ TEM Observation of the Behavior of an Individual Fullerene-Like MoS2 Nanoparticle in a Dynamic Contact

Author

Imène Lahouij, Béatrice Vacher, Fabrice Dassenoy, Jean Michel Martin, Ludvig de Knoop, Centre de Mise en Forme des Matériaux (CEMEF), MINES ParisTech - École nationale supérieure des mines de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Fullerene, Mechanical Engineering, Rolling resistance, Friction modifier, Nanoparticle, Nanotechnology, 02 engineering and technology, Surfaces and Interfaces, Tribology, 021001 nanoscience & nanotechnology, Exfoliation joint, [SPI.MAT]Engineering Sciences [physics]/Materials, Surfaces, Coatings and Films, Shear (sheet metal), 020303 mechanical engineering & transports, 0203 mechanical engineering, Mechanics of Materials, Lubrication, Composite material, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

Inorganic fullerene-(IF)-like nanoparticles made of metal dichalcogenides (IF-MoS2, IF-WS2) have been known to be effective as anti-wear and friction modifier additives under boundary lubrication. The lubrication mechanism of these nanoparticles has been widely investigated in the past and even if the exfoliation and third body transfer of molecular sheets onto the asperities constitute the prevalent mechanism for the improved tribological behavior of IF nanoparticles, it has also been suggested that a rolling friction process could also play a role for well crystallized and spherical particles. In this study, in situ Transmission Electron Microscopy (TEM) observations of the behavior of single IF-MoS2 nanoparticles were conducted using a sample holder that combines TEM and Atomic Force Microscopy (AFM) which simultaneously can apply normal and shear loads. It was shown that depending on the test conditions, either a rolling process or a sliding of the fullerenes could be possible. These in situ TEM observations are the first carried out with IF nanoparticles.

Published
2011
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5. Three Dimensional Visualization of Electromagnetic Fields from One Dimensional Nanostructures

Author

Aurélien Masseboeuf, Christophe Gatel, Martin Hÿtch, Charudatta Phatak, Ludvig de Knoop, Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Electromagnetic field, Physics, [PHYS]Physics [physics], Nanostructure, business.industry, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Optics, Three dimensional visualization, 0103 physical sciences, 0210 nano-technology, business, Instrumentation, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015
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6. Absorption of crystal/amorphous interfacial dislocations during in situ TEM nanoindentation of an Al thin film on Si

Author

Marc Legros, Ludvig de Knoop, Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)

Subjects
Finite element method, Materials science, Thin films, 02 engineering and technology, 01 natural sciences, Nanoindentation, Crystal, Interfacial dislocations, Indentation, 0103 physical sciences, Interfaces (materials), General Materials Science, In-situ TEM, Composite material, Thin film, Metallic thin films, Absorption (electromagnetic radiation), Room temperature, 010302 applied physics, [PHYS]Physics [physics], Mechanical Engineering, Al thin films, Direct observations, Metals and Alloys, Threading dislocation, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Amorphous solid, Finite element modelling, Crystallography, Dislocations (crystals), Mechanics of Materials, Transmission electron microscopy, Dislocation, 0210 nano-technology, Aluminum
Abstract

cited By 6; International audience; Indentation of an Al film cross-section in situ in a transmission electron microscope at room temperature provides a direct observation of the absorption of threading dislocations by the metal/amorphous interface. The process occurs at a stress of about 100 MPa, a value that has been both calculated using finite-element modelling and directly measured from the dislocation radii. These results indicate that the strength of metallic thin films on oxidized substrates may therefore be weakly dependent on threading and interfacial dislocations.

Published
2014
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7. Determining the work function of a carbon-cone cold-field emitter by in situ electron holography

Author

Florent Houdellier, Ludvig de Knoop, Marc Monthioux, Aurélien Masseboeuf, Christophe Gatel, Martin Hÿtch, Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Modélisation et Exploration des Matériaux (MEM), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Service de Physique des Matériaux et Microstructures (SP2M - UMR 9002), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
010302 applied physics, [PHYS]Physics [physics], Materials science, Field (physics), General Physics and Astronomy, 02 engineering and technology, Cell Biology, 021001 nanoscience & nanotechnology, 01 natural sciences, Electron holography, Field electron emission, Structural Biology, Transmission electron microscopy, Electric field, 0103 physical sciences, General Materials Science, Work function, Atomic physics, 0210 nano-technology, Voltage, Common emitter
Abstract

International audience; Cold-field emission properties of carbon cone nanotips (CCnTs) have been studied in situ in the transmission electron microscope (TEM). The current as a function of voltage, i(V), was measured and analyzed using the Fowler–Nordheim (F–N) equation. Off-axis electron holography was employed to map the electric field around the tip at the nanometer scale, and combined with finite element modeling, a quantitative value of the electric field has been obtained. For a tip-anode separation distance of 680 nm (measured with TEM) and a field emission onset voltage of 80 V, the local electric field was 2.55 V/nm. With this knowledge together with recorded i(V) curves, a work function of 4.8 ± 0.3 eV for the CCnT was extracted using the F–N equation.

Published
2014
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