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279 results on '"Pierre Ruterana"'

1. Comparative studies of interatomic potentials for modeling point defects in wurtzite GaN

Author: Huaping Lei, Jun Chen, and Pierre Ruterana
Subjects: Physics, QC1-999
Abstract: In this paper, a new version of the Stillinger–Weber (SW) potential for wurtzite GaN is presented, by which we systematically explore the structural and thermodynamical properties of native point defects and their complexes. In parallel, the semi-empirical Modified Embedded-Atom Method (MEAM) potential is selected for comparison. The SW and MEAM potentials are assessed by the reproduction of the fundamental properties of wurtzite GaN and by the ability to describe the inversion domain boundaries and the wurtzite–rocksalt phase transition. Then the structural search of native point defects and their complexes in GaN is implemented using both SW and MEAM potentials with the benchmark of Density Functional Theory (DFT) calculations. Besides vacancies and antisites, four N and five Ga interstitials are confirmed by refining the DFT calculations, among which two N split interstitials N+−N⟨21̄1̄0⟩ and N+−Ga⟨011̄0⟩, and two Ga split interstitials, Ga+−Ga⟨011̄0⟩−g and Ga+−N⟨011̄0⟩, are observed for the first time. The SW potential correctly predicts the octahedral occupation GaOct to be the most stable Ga interstitial, while the MEAM potential predicts the ground state of the N+−N⟨011̄0⟩ split interstitial (N+−N⟨011̄0⟩−g) as the most stable N interstitial. However, neither of the two potentials could simultaneously generate the most stable configurations of N and Ga interstitials. The investigations of point defect complexes reveal that N octahedral Frenkel [FrenkelOct(N)] and paired antisite (NGaGaN) defects are unstable and get converted into VN⊕N+−N⟨011̄0⟩−g configurations with different separations between VN and N+−N⟨011̄0⟩−g point defects based on the DFT calculations. The formation energies calculated by the DFT and SW potential demonstrate that Schottky, Ga octahedral Frenkel [FrenkelOct(Ga)], and VN⊕N+−N⟨011̄0⟩−g point defect complexes are energetically feasible and that they should not dissociate into two isolated point defects. In contrast, the MEAM potential predicts the dissociation to be exothermic for Schottky and VN⊕N+−N⟨011̄0⟩−g. Overall, the structural features concerned with N–N or Ga–Ga bonds relaxed by the SW potential are more consistent with DFT calculations than the MEAM counterpart.
Published: 2023
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2. Transition from Screw-Type to Edge-Type Misfit Dislocations at InGaN/GaN Heterointerfaces

Author: Quantong Li, Albert Minj, Yunzhi Ling, Changan Wang, Siliang He, Xiaoming Ge, Chenguang He, Chan Guo, Jiantai Wang, Yuan Bao, Zhuming Liu, and Pierre Ruterana
Subjects: InGaN/GaN heterostructures, transmission electron microscopy, indium composition, screw-type dislocations, edge-type misfit dislocations, Crystallography, QD901-999
Abstract: We have investigated the interface dislocations in InxGa1−xN/GaN heterostructures (0 ≤ x ≤ 0.20) using diffraction contrast analysis in a transmission electron microscope. The results indicate that the structural properties of interface dislocations depend on the indium composition. For lower indium composition (up to x = 0.09), we observed that the screw-type dislocations and dislocation half-loops occurred at the interface, even though the former do not contribute toward elastic relaxation of the misfit strain in the InGaN layer. With the increase in indium composition (0.13 ≤ x ≤ 0.17), in addition to the network of screw-type dislocations, edge-type misfit dislocations were generated, with their density gradually increasing. For higher indium composition (0.18 ≤ x ≤ 0.20), all of the interface dislocations are transformed into a network of straight misfit dislocations along the direction, leading to partial relaxation of the InGaN epilayer. The presence of dislocation half-loops may be explained by a slip on basal plane; formation of edge-type misfit dislocations are attributed to punch-out mechanism.
Published: 2023
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3. TOPOLOGICAL LOCALISATION OF DEFECTS AT ATOMIC SCALE

Author: Jean-Paul Jernot, Patricia Jouannot-Chesney, Christian Lantuéjoul, Gérard Nouet, and Pierre Ruterana
Subjects: defects, Euler-Poincare characteristic, HREM images, interfaces, tessellations, topology, Medicine (General), R5-920, Mathematics, QA1-939
Abstract: The problem addressed in this paper is the detection of defects on atomic structures. The procedure proposed is in two steps. At first a tessellation is built starting from the atoms. It consists of a partition of the space into cells, and is used to define the neighbourhood relationships between the atoms. Then, the local contribution to a topological parameter, namely the Euler-Poincare characteristic, is defined and measured for each cell. Within a regular tessellation, made of identical cells, this local contribution is equal to zero. Any local deviation from regularity corresponds to a tessellation containing cells with non-zero contributions. This allows us to locate the defects from a topological criterion and opens the way to a fully automatic detection of interfaces at atomic scale. The procedure is applied in 2D space for the detection of edge dislocations, grain boundaries and twins from HREM models and images. A 3D example is also given to illustrate its generality.
Published: 2011
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4. Atomic Plane Misorientation Assisted Crystalline Quality Improvement in Epitaxial Growth of AlN on a Nanopatterned Sapphire (0001) Surface for Deep Ultraviolet Photoelectric Devices

Author: Yong Deng, Nan Xie, Wenyu Hu, Zhenyu Ma, Fujun Xu, Longqing Chen, Wenbin Qiu, Lin Zhao, Hong Tao, Bo Wu, Yi Huang, Jian Ma, Xiaoyi Wang, Xuqi Zhang, Yang Qiu, Xudong Cui, Chaoyuan Jin, Marie-Pierre Chauvat, Pierre Ruterana, and Thomas Walther
Subjects: General Materials Science
Published: 2023
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5. Nitride Semiconductors: Handbook on Materials and Devices

Author: Pierre Ruterana, Martin Albrecht, Jörg Neugebauer, Pierre Ruterana, Martin Albrecht, Jörg Neugebauer
Published: 2006

6. Stress relaxation in III-V nitrides: investigation of metallic atoms interaction with the N-vacancy

Author: Rofka Ramdani, Viwanou Hounkpati, Jun Chen, Pierre Ruterana, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), ANR-11-LABX-0014,GANEX,Réseau national sur GaN(2011), and European Project: 662322,H2020,ECSEL-2014-1,OSIRIS(2015)
Subjects: [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Physics and Astronomy
Abstract: Molecular dynamics simulations have been carried out to study the interaction between two point defects in III-nitride materials (AlN, GaN and InN): a substitutional metal atom (indium, aluminum, gallium) and the N-vacancy. The Stillinger-Weber (S-W) empirical potential is used. By calculating the potential energies of different configurations with these two defects, it is shown that the indium atom in AlN and GaN or aluminum and gallium in InN are stable in the immediate vicinity of the N-vacancy. In contrast, the gallium atom in AlN and the aluminum atom in GaN may be difficult to bring near the N-vacancy. This behavior is related to the stress relaxation in the presence of these point defects. In AlN, the stability of indium atoms around the N-vacancy is the highest, indicating a good probability of aggregation, which may constitute a first explanation for the reported phase segregation during the growth of InAlN alloys.
Published: 2022
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7. Incorporation of Europium into GaN Nanowires by Ion Implantation

Author: Wolfhard Möller, Bruno Daudin, Eduardo Alves, M. Felizardo, D. Nd. Faye, Emilio Nogales, Mathieu Kociak, T. Auzelle, Luiz H. G. Tizei, Katharina Lorenz, Marco Peres, Bianchi Méndez, Andrés Redondo-Cubero, Pierre Ruterana, X. Biquard, Instituto de Plasmas e Fusão Nuclear [Lisboa] (IPFN), Instituto Superior Técnico, Universidade Técnica de Lisboa (IST), Nanostructures et Rayonnement Synchrotron (NRS ), Modélisation et Exploration des Matériaux (MEM), 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)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Departamento de Física de Materiales [Madrid], Universidad Autonoma de Madrid (UAM), Nanophysique et Semiconducteurs (NPSC), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), 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), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institute of Ion Beam Physics and Materials Research [Dresden], Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Universidad Autónoma de Madrid (UAM), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, genetic structures, Annealing (metallurgy), Nanowire, chemistry.chemical_element, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Ion, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Physical and Theoretical Chemistry, Thin film, Nanoscopic scale, Física de materiales, business.industry, Doping, 021001 nanoscience & nanotechnology, eye diseases, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, General Energy, Ion implantation, chemistry, Física del estado sólido, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, sense organs, 0210 nano-technology, business, Europium
Abstract: International audience; Rare earth (RE)-doped GaN nanowires (NWs), combining the well-defined and controllable optical emission lines of trivalent RE ions with the high crystalline quality, versatility, and small dimension of the NW host, are promising building blocks for future nanoscale devices in optoelectronics and quantum technologies. Europium doping of GaN NWs was performed by ion implantation, and structural and optical properties were assessed in comparison to thin film reference samples. Despite some surface degradation for high implantation fluences, the NW core remains of high crystalline quality with lower concentrations of extended defects than observed in ion-implanted thin films. Strain introduced by implantation defects is efficiently relaxed in NWs and the measured deformation stays much below that in thin films implanted in the same conditions. Optical activation is achieved for all samples after annealing, and while optical centers are similar in all samples, Eu3+ emission from NW samples is shown to be less affected by residual implantation damage than for the case of thin films. The incorporation of Eu in GaN NWs was further investigated by nano-cathodoluminescence and X-ray absorption spectroscopy (XAS). Maps of the Eu-emission intensity within a single NW agree well with the Eu-distribution predicted by Monte Carlo simulations, suggesting that no pronounced Eu-diffusion takes place. XAS shows that 70–80% of Eu is found in the 3+ charge state while 20–30% is 2+ attributed to residual implantation defects. A similar local environment was found for Eu in NWs and thin films: for low fluences, Eu is mainly incorporated on substitutional Ga-sites, while for high fluences XAS points at the formation of a local EuN-like next neighbor structure. The results reveal the high potential of ion implantation as a processing tool at the nanoscale.
Published: 2019
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8. Directional charge transportation and Rayleigh scattering for the optimal in-band quantum yield of a composite semiconductor nano-photocatalyst

Author: Pierre Ruterana, Min Xu, Yi Huang, Xueqing Wang, Jian Ma, Chaoyuan Jin, Yang Qiu, Xudong Cui, Xiaoyi Wang, Wenyu Hu, Feng Miao, Southwest Minzu University [Chengdu], Huzhou University [Zhejiang], Southern University of Science and Technology (SUSTech), Leshan Normal University, Southwest University of Science and Technology [Mianyang] (SWUST), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Southern University of Science and Technology [Shenzhen] (SUSTech), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Photon, [PHYS.PHYS]Physics [physics]/Physics [physics], business.industry, Fermi level, Quantum yield, Physics::Optics, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Catalysis, Fluorescence spectroscopy, 0104 chemical sciences, symbols.namesake, Semiconductor, symbols, [CHIM.CRIS]Chemical Sciences/Cristallography, Optoelectronics, Rayleigh scattering, 0210 nano-technology, business, Fermi gas, Visible spectrum
Abstract: In this work, we propose a novel technique based on wavelength dispersive in situ fluorescence spectroscopy (WDIFS) for diagnosing the wavelength-dependent directional charge transportation and Rayleigh scattering enhanced in-band quantum yield. For the first time, it is clearly demonstrated that the formation of the 2D electron gas in CuO/ZnO and upward Schottky barriers in ZnO/Ag facilitate the photocatalytic performance in the ultraviolet spectral range, and that utilization of the visible spectrum relies on the band alignment between the energy level of the dopants and the Fermi level of Ag. Moreover, it is shown that the wavelength-dependent in-band quantum yield can be controlled through particle size photon scattering, in which the strong Rayleigh scattering based photon harvesting brings about a significant increase in the photocatalytic performance in the ultraviolet spectrum. Eventually, it is forecast that systematic use of the proposed technique for a systematic diagnosis should help towards the production of efficient ZnO-based photocatalysts.
Published: 2021
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9. Exploration of irradiation intensity dependent external in-band quantum yield for ZnO and CuO/ZnO photocatalysts

Author: Yi Huang, Dongyang Li, Gang Chen, Jiaxuan Wei, Pierre Ruterana, Rui Han, Qiuping Zhang, Jian Ma, Zhonghao Wu, Wenyu Hu, Xudong Cui, Chunhong Li, Xiaoyi Wang, Feng Miao, Kaiyi Luo, Min Xu, Southwest Minzu University [Chengdu], Xihua University (XHU), Southwest University of Science and Technology [Mianyang] (SWUST), Sichuan University [Chengdu] (SCU), Huzhou University [Zhejiang], Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Oxide, General Physics and Astronomy, Quantum yield, 02 engineering and technology, 010402 general chemistry, Photochemistry, 01 natural sciences, Effective nuclear charge, Metal, chemistry.chemical_compound, Condensed Matter::Materials Science, Band diagram, [CHIM.CRIS]Chemical Sciences/Cristallography, Irradiation, Physical and Theoretical Chemistry, [PHYS.PHYS]Physics [physics]/Physics [physics], business.industry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Semiconductor, chemistry, visual_art, Photocatalysis, visual_art.visual_art_medium, 0210 nano-technology, business
Abstract: Decorating metal oxides with wide band-gap semiconductor nano-particles constitute an important approach for synthesizing nano-photocatalysts, where the photocatalytic activity is attributed to the band diagram related effective charge separation and external in-band quantum yield (EIQY). However, up to now, the correlation between the irradiation intensity and the functionalization of the in-band quantum yield has not yet been explained. In this work, by investigating the photocatalytic activity of ZnO and CuO/ZnO (CZO) nano-photocatalysts under various irradiative intensities, we show that the effective charge separation in the CuO/ZnO band alignment is sensitive to weak illumination, while ZnO exhibits a competitive photocatalytic activity with CZO under strong illumination. As a consequence, by modifying the irradiation intensity, the intrinsic ZnO can achieve a similar photocatalytic activity to that of metal oxide decorated ZnO. Besides, the optimal photocatalytic activity of CZO is found to be reachable by manipulating the pollutant concentration.
Published: 2021
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10. Cleaning and nitridation of (100) GaAs surfaces: a high resolution electron microscopy study

Author: N Bonnet, J. P. Chevalier, P. Friedel, and Pierre Ruterana
Subjects: congenital, hereditary, and neonatal diseases and abnormalities, Materials science, Passivation, business.industry, Resolution (electron density), Oxide, nutritional and metabolic diseases, High resolution, Plasma, law.invention, chemistry.chemical_compound, chemistry, law, Optoelectronics, Electron microscope, business, Layer (electronics)
Abstract: Native oxides play a crucial role in the parasitic electrical effects of GaAs surface and for passivation to be effective these have to be eliminated. Si3N4 can then be deposited as an encapsulating layer. We report high resolution cross-sectional electron microscopy of GaAs/oxide interfaces at various process stages as well as of the GaAs/Si3N4 interface after cleaning and nitridation in multipolar plasmas.
Published: 2021
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11. Transient annealing of implanted silicon: microscopic analysis and comparison with electrical characteristics

Author: Pierre Ruterana, M.C. Boissy, and G. Nouet
Subjects: Materials science, Silicon, chemistry, business.industry, Annealing (metallurgy), Optoelectronics, chemistry.chemical_element, business
Published: 2020
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12. Indium segregation mechanism and V-defects formation on (0001) InAlN surface: an ab-initio investigation

Author: Pierre Ruterana, Ranim Mohamad, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Institut des Matériaux Jean Rouxel (IMN), Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Surface (mathematics), [PHYS]Physics [physics], Materials science, Acoustics and Ultrasonics, Diffusion, Ab initio, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Epitaxy, 01 natural sciences, Molecular physics, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Adsorption, chemistry, Aluminium, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM]Chemical Sciences, First principle, 0210 nano-technology, Indium
Abstract: First-principle calculations were performed to investigate adsorption and diffusion of indium and aluminum atoms on (0001) and (0001) In (18%) AlN surfaces. First, it was shown that these surfaces are most stable when they contain complex defects. The presence of vacancies causes the In to be strongly bound to the surface with the adsorption energy increasing by 0.11 eV for metal-polar and by 0.78 eV N-polar. In contrast, the adsorption strength of Al to the surface with defects decreases; the corresponding energy goes from 3.96 eV–2.29 eV (metal-polar) and from 8.30 eV–5.05 eV (N-polar). Simultaneously, the diffusion of In is enhanced; its energy barrier decreases by 0.74 eV (0.06 eV) for the N-polar (metal-polar) InAlN surface, whereas that of the Al adatom increases by 0.32 eV for metal-polar (0.08 eV for N-polar), which should limit its diffusion on the surface. Therefore, the indium atoms will tend to migrate towards the complex defects. Eventually, during epitaxial growth, this aggregation of indium atoms around the defects and the low mobility of Al atoms could be the origin of the observed V defects, the phase separation and the crystallographic degradation of the InAlN epitaxial layers with increasing thickness.
Published: 2020
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13. The microstructure, local indium composition and photoluminescence in green-emitting InGaN/GaN quantum wells

Author: M. P. Chauvat, Pierre Ruterana, Andreas Rosenauer, Thi Huong Ngo, Nicolas Chery, Tim Grieb, Bernard Gil, Knut Müller-Caspary, Aimeric Courville, P. de Mierry, Marco Schowalter, Benjamin Damilano, Thorsten Mehrtens, and Florian F. Krause
Subjects: 010302 applied physics, Histology, Photoluminescence, Materials science, business.industry, chemistry.chemical_element, Heterojunction, 02 engineering and technology, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, Pathology and Forensic Medicine, chemistry, 0103 physical sciences, Scanning transmission electron microscopy, Optoelectronics, Metalorganic vapour phase epitaxy, 0210 nano-technology, business, Chemical composition, Quantum well, Indium
Abstract: In this work, we analyse the microstructure and local chemical composition of green-emitting Inx Ga1-x N/GaN quantum well (QW) heterostructures in correlation with their emission properties. Two samples of high structural quality grown by metalorganic vapour phase epitaxy (MOVPE) with a nominal composition of x = 0.15 and 0.18 indium are discussed. The local indium composition is quantitatively evaluated by comparing scanning transmission electron microscopy (STEM) images to simulations and the local indium concentration is extracted from intensity measurements. The calculations point out that the measured indium fluctuations may be correlated to the large width and intensity decrease of the PL emission peak.
Published: 2017
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14. The structure of InAlGaN layers grown by metal organic vapour phase epitaxy: effects of threading dislocations and inversion domains from the GaN template

Author: Pierre Ruterana, H. Ben Ammar, Cedric Lacam, Piero Gamarra, Magali Morales, Albert Minj, and M. P. Chauvat
Subjects: 010302 applied physics, Histology, Materials science, Morphology (linguistics), business.industry, 02 engineering and technology, High-electron-mobility transistor, Pinhole, 021001 nanoscience & nanotechnology, 01 natural sciences, Pathology and Forensic Medicine, Metal, Crystallography, visual_art, 0103 physical sciences, visual_art.visual_art_medium, Optoelectronics, Metalorganic vapour phase epitaxy, Dislocation, 0210 nano-technology, business, Layer (electronics), Hillock
Abstract: Defects in quaternary InAlGaN barriers and their effects on crystalline quality and surface morphology have been studied. In addition to growth conditions, the quality of the GaN template may play an important role in the formation of defects in the barrier. Therefore, this work is focused on effects caused by threading dislocations (TDs) and inversion domains (IDs) originating from the underlying GaN. The effects are observed on the crystalline quality of the barrier and characteristic surface morphologies. Each type of TDs is shown to affect the surface morphology in a different way. Depending on the size of the corresponding hillock for a given pinhole, it was possible to determine the dislocation type. It is pointed out that the smallest pinholes are not connected to TDs whereas the large ones terminate either mixed type or edge type TDs. At sufficiently large layer thickness, the IDs originating from the GaN template lead to the formation of concentric trenches at the layer surface, and this is related to the change in growth kinetics on top and at the immediate surroundings of the ID.
Published: 2017
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15. Effective absorption correction for energy dispersive X-ray mapping in a scanning transmission electron microscope: analysing the local indium distribution in rough samples of InGaN alloy layers

Author: X. Wang, Thomas Walther, Pierre Ruterana, and M. P. Chauvat
Subjects: 010302 applied physics, Histology, Materials science, business.industry, chemistry.chemical_element, 02 engineering and technology, Surface finish, 021001 nanoscience & nanotechnology, 01 natural sciences, Pathology and Forensic Medicine, Optics, chemistry, 0103 physical sciences, Scanning transmission electron microscopy, Cathode ray, 0210 nano-technology, Absorption (electromagnetic radiation), business, Spectroscopy, Optical path length, Indium, Beam (structure)
Abstract: We have applied our previous method of self-consistent k*-factors for absorption correction in energy-dispersive X-ray spectroscopy to quantify the indium content in X-ray maps of thick compound InGaN layers. The method allows us to quantify the indium concentration without measuring the sample thickness, density or beam current, and works even if there is a drastic local thickness change due to sample roughness or preferential thinning. The method is shown to select, point-by-point in a two-dimensional spectrum image or map, the k*-factor from the local Ga K/L intensity ratio that is most appropriate for the corresponding sample geometry, demonstrating it is not the sample thickness measured along the electron beam direction but the optical path length the X-rays have to travel through the sample that is relevant for the absorption correction.
Published: 2017
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16. Composition dependent activity of Fe 1−x Pt x decorated ZnCdS nanocrystals for photocatalytic hydrogen evolution

Author: Yang Li, Hao Wang, Pierre Ruterana, Xina Wang, Yi Wang, Hanbin Wang, Dan Shu, Xiang Liu, Xu Chen, and Xiao-Niu Peng
Subjects: Materials science, Base (chemistry), Alloy, Energy Engineering and Power Technology, Nanoparticle, Nanotechnology, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, chemistry.chemical_compound, chemistry.chemical_classification, Nanocomposite, Renewable Energy, Sustainability and the Environment, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, Fuel Technology, chemistry, Nanocrystal, engineering, Photocatalysis, 0210 nano-technology, Ethylene glycol, Visible spectrum, Nuclear chemistry
Abstract: In this work, ZnCdS nanoparticles (NPs) were decorated with FePt alloy, forming nanocomposites via ethylene glycol reduction method. The photocatalytic H 2 production of the Fe 1−x Pt x –ZnCdS NPs was studied by changing the composition and weight percentage of Fe 1−x Pt x alloy in the nanocomposites under visible light (λ ≥ 420 nm) irradiation. The results showed that the hydrogen production rate of Fe 1−x Pt x –ZnCdS NPs had a significant enhancement over the pure ZnCdS (740 μmol g −1 h −1 ). The activity of the nanocomposites was dependent on the composition of Fe 1−x Pt x alloy and the highest hydrogen production rate of 2265 μmol g −1 h −1 was achieved by the 0.5 wt% Fe 0.3 Pt 0.7 –ZnCdS nanocomposites, which was even better than that of 0.5 wt% Pt–ZnCdS (1626 μmol g −1 h −1 ) under the same condition. This study highlights the significance of Pt base alloys as new cocatalysts for the development of novel composite photocatalysts.
Published: 2017
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17. Impact of Gate–Drain Spacing on Low-Frequency Noise Performance of In Situ SiN Passivated InAlGaN/GaN MIS-HEMTs

Author: Farid Medjdoub, Laurence Méchin, Pierre Ruterana, Cedric Lacam, Jean-Marc Routoure, Mehdi Rzin, Bruno Guillet, Piero Gamarra, and Magali Morales
Subjects: 010302 applied physics, Materials science, Noise measurement, business.industry, Infrasound, Transistor, Order (ring theory), 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Electronic, Optical and Magnetic Materials, law.invention, Barrier layer, 13. Climate action, law, Logic gate, 0103 physical sciences, Optoelectronics, Electrical and Electronic Engineering, 0210 nano-technology, business, Layer (electronics), Noise (radio)
Abstract: In this paper we investigated the gate–drain access region spacing ( $L_{\mathrm {GD}})$ effect on electrical and noise performance of InAlGaN/GaN metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) using in situ SiN cap layer as gate insulator. Different $L_{\mathrm {GD}}$ of InAlGaN/GaN MIS-HEMTs using sub-10 nm barrier layer are studied. Low-frequency noise measurements have been carried out for the first time in order to analyze the impact of the gate–drain spacing on the electrical characteristics. The noise of the channel under the gate has been identified as the dominant channel noise source for $L_{\mathrm {GD}} . Finally, the calculated Hooge parameter ( $\alpha _{H})$ is equal to $3.1\times 10^{-4}$ . It reflects the high material quality while using sub-10 nm InAlGaN layer, which is promising for high-frequency applications.
Published: 2017
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18. Effect of AlGaN interlayer on the GaN/InGaN/GaN/AlGaN multi-quantum wells structural properties toward red light emission

Author: Bernard Gil, Benjamin Damilano, Kaddour Lekhal, Thi Huong Ngo, Pierre Ruterana, Magali Morales, Nicolas Chery, M. P. Chauvat, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and Université Nice Sophia Antipolis (1965 - 2019) (UNS)
Subjects: 010302 applied physics, Diffraction, Photoluminescence, Materials science, business.industry, General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, Wavelength, Stack (abstract data type), Transmission electron microscopy, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, 0210 nano-technology, business, Layer (electronics), Quantum well
Abstract: International audience; In this work, InGaN/GaN Multi-Quantum Wells (MQWs) with strain compensating AlGaN interlayers grown by metalorganic vapour phase epitaxy have been investigated by high resolution X-ray diffraction, transmission electron microscopy and photoluminescence (PL). For different AlGaN strain compensating layer thicknesses varying from 0 to 10.6 nm, a detailed X-ray diffraction analysis shows that the MQW stack become completely strained on GaN along a and c. The compensation is full from an AlGaN layer thickness of 5.2 nm, and this does not change up to the largest one that has been investigated. In this instance, the AlGaN was grown at the same temperature as the GaN barrier, on top of a protective 3 nm GaN. It is found that the crystalline quality of the system is progressively degraded when the thickness of the AlGaN interlayer is increased through strain concentrated domains which randomly form inside the 3 nm GaN low temperature layer. These domains systematically contribute to a local decrease of the QW thickness and most probably to an efficient localisation of carriers. Despite these defects, the PL is highly improved towards the red wavelengths and compares with the reports on ultrathin AlGaN layers where this has been correlated to the improvement of the crystalline quality although with less strain compensation.
Published: 2020
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19. The [10-10] edge dislocation in the wurtzite structure: A high-resolution transmission electron microscopy investigation of [0001] tilt grain boundaries in GaN and ZnO

Author: Pierre Ruterana, Siqian Li, Jun Chen, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Materials science, Polymers and Plastics, Condensed matter physics, [PHYS.PHYS]Physics [physics]/Physics [physics], Resolution (electron density), Metals and Alloys, Dangling bond, 02 engineering and technology, Electronic structure, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Ring (chemistry), 01 natural sciences, Electronic, Optical and Magnetic Materials, Transmission electron microscopy, 0103 physical sciences, Ceramics and Composites, [CHIM.CRIS]Chemical Sciences/Cristallography, Grain boundary, Dislocation, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Wurtzite crystal structure
Abstract: A detailed topological analysis and atomic structure investigation of [0001] tilt grain boundaries (GBs) in GaN and ZnO has been carried out using atomistic simulation and high-resolution transmission electron microscopy (TEM). The analysis of Σ7 asymmetric GBs in GaN, shows that they are only made of well-separated a = 1 3 11 2 ¯ 0 > edge dislocations based on the three basic structural units: 4-, 8- and 57-atom rings. In this compound, the Burgers vectors adapt their orientations in order to accommodate the rotation angle of the grain boundary. However, in ZnO, the topology of such GBs is shown to comprise two types of dislocation contents: one of them follows the behavior of GaN in which individual a edge dislocations are dominant; the second is the [ 10 1 ¯ 0 ] edge dislocation which comes out as a distinct structure with a large core as pointed out in the Σ13 (27.8°/32.2°) GBs. The determined low-energy configuration of this [ 10 1 ¯ 0 ] dislocation is made of connected 4-8-6-atom rings in agreement with an early proposal of its possible geometrical model. The electronic structure of these GB dislocations shows the evidence of a deep state induced above the valence band edge in all the structural units comprising the 57-atom ring. In contrast to previous reports which solely ascribed such states to dangling bonds, this one is ascribed to the cooperative effect of Zn–Zn wrong bonds and broken O–O bonds inside the 57-atomic ring.
Published: 2019
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20. Effect of the residual doping on the performance of InN epilayers as saturable absorbers for ultrafast lasers at 1.55µm

Author: Marco Jiménez-Rodríguez, Pierre Ruterana, Fernando B. Naranjo, L. Monroy, Miguel Gonzalez-Herraez, Eva Monroy, Universidad de Alcalá. Departamento de Electrónica, Departamento de Electronica, Grupo de Ingenieria Fotonica, Universidad de Alcalá - University of Alcalá (UAH), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Nanophysique et Semiconducteurs (NPSC), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), 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), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)
Subjects: Materials science, Physics::Optics, 02 engineering and technology, Substrate (electronics), 01 natural sciences, law.invention, 010309 optics, [SPI]Engineering Sciences [physics], law, Fiber laser, 0103 physical sciences, business.industry, Doping, Saturable absorption, 021001 nanoscience & nanotechnology, Laser, Electronic, Optical and Magnetic Materials, Active layer, Wavelength, Optoelectronics, Electrónica, Electronics, 0210 nano-technology, business, Ultrashort pulse
Abstract: We report on the improvement of performance of InN-based saturable absorbers in fiber lasers operating at 1.55 mum by reducing the residual doping, due to the lower Burstein-Moss effect. The improved tuning of the band-to-band transition with respect to the operation wavelength leads to an enhancement of nonlinear optical effects, resulting in 30 % of modulation depth. We introduce the development of an ultrafast mode-locked fiber laser using an improved InN-based saturable absorber that incorporates a buffer layer between the active layer and the substrate. The laser delivers output pulses with a temporal width of 220 fs, a repetition rate of 5.25 MHz, and high-pulse energy of 5.8 nJ., Ministerio de Economía, Industria y Competitividad, Ministerio de Ciencia, Innovación y Universidades, Comunidad de Madrid
Published: 2019
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21. The critical role of N-vacancy on chemical composition fluctuations and degradation of InAlN layer

Author: Sławomir Kret, Marie Pierre Chauvat, Cedric Lacam, Sylvain Delage, Pierre Ruterana, Ranim Mohamad, Viwanou Hounkpati, Piero Gamarra, Jun Chen, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Institute of Physics [Warsaw] (IFPAN), Polish Academy of Sciences (PAN), Alcatel-Thales III-V Lab (III-V Lab), THALES, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), THALES [France], Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institute of Physics, Polska Akademia Nauk (PAN), Laboratoire de Recherches de THOMSON-CSF (LCR-THOMSON-CSF), Thomson, État Mécanique et Microstructure des Matériaux (E3M), Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, and Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Indium nitride, Fabrication, Materials science, Alloy, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, engineering.material, 01 natural sciences, law.invention, chemistry.chemical_compound, law, Vacancy defect, Lattice (order), 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Chemical composition, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, [PHYS.PHYS]Physics [physics]/Physics [physics], business.industry, Transistor, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, chemistry, engineering, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, 0210 nano-technology, business, Indium
Abstract: Due to its intrinsic properties and the possible lattice match to GaN, InAlN is expected to allow the fabrication of optimal high electron mobility transistors for high power and high frequency applications. However, the crystal quality of InAlN nearly lattice-matched to GaN degrades when the layer thickness is increased, and this is a strong limitation for the fabrication of devices in which thick barriers need to be used. In this work, we have carried out a detailed theoretical investigation of the behavior of indium atoms in the alloy. It is clearly shown that in the presence of nitrogen vacancies, which are common defects in these materials, indium nitride clusters will present excess formation energy up to diameters around 1.4 nm. In parallel, Z-contrast TEM observations close to the InAlN/GaN interface show that 2–5 nm size indium rich areas form and are systematically connected to the vertical degradation channels. This is at variance with published results, which concluded that the observed degradation was exclusively either due to the underlying threading dislocations or due to a characteristic three-dimensional growth mode.
Published: 2019
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22. Evidence of relationship between strain and In-incorporation: Growth of N-polar In-rich InAlN buffer layer by OMCVD

Author: M. P. Chauvat, Jaroslav Kováč, Pierre Ruterana, Sławomir Kret, Peter Siffalovic, Martin Kuball, Jan Kuzmik, Prerna Chauhan, Ľubomír Vančo, F. Gucmann, Edmund Dobročka, Albert Minj, Stanislav Hasenöhrl, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), H. H. Wills Physics Laboratory [Bristol], University of Bristol [Bristol], Institute for Solid-State Electronics, TU Vienna, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, BAND-GAP, Analytical chemistry, General Physics and Astronomy, 02 engineering and technology, FILMS, 01 natural sciences, Physics, Applied, organometallic chemical vapor deposition, In-rich In_x Al_(1-x)N layer, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, NITRIDE, CDTR, high-resolution transmission electron microscopy, Metalorganic vapour phase epitaxy, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, High-resolution transmission electron microscopy, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, atomic scanning transmission electron microscopy, Auger electron spectroscopy, Science & Technology, Strain (chemistry), [PHYS.PHYS]Physics [physics]/Physics [physics], ORIGIN, Physics, Relaxation (NMR), OPTICAL-PROPERTIES, DEFECTS, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, THREADING DISLOCATIONS, ALINN, Transmission electron microscopy, Physical Sciences, Sapphire, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, 0001 SAPPHIRE, 0210 nano-technology, Layer (electronics), GAN LAYERS
Abstract: © 2019 Author(s). Two I n x A l 1 - x N layers were grown simultaneously on different substrates [sapphire (0001) and the Ga-polar GaN template], but under the same reactor conditions, they were employed to investigate the mechanism of strain-driven compositional evolution. The resulting layers on different substrates exhibit different polarities and the layer grown on sapphire is N-polar. Moreover, for the two substrates, the difference in the degree of relaxation of the grown layers was almost 100%, leading to a large In-molar fraction difference of 0.32. Incorporation of In in I n x A l 1 - x N layers was found to be significantly influenced by the strain imposed by the under-layers. With the evolutionary process of In-incorporation during subsequent layer growth along [0001], the direction of growth was investigated in detail by Auger electron spectroscopy. It is discovered that the I n 0.60 A l 0.40 N layer grown directly on sapphire consists of two different regions with different molar fractions: the transition region and the uniform region. According to the detailed cross-sectional transmission electron microscopy, the transition region is formed near the hetero-interface due to the partial strain release caused by the generation of misfit-dislocations. The magnitude of residual strain in the uniform region decides the In-molar fraction. I n x A l 1 - x N layers were analyzed by structural and optical characterization techniques. Our present work also shows that a multi-characterization approach to study I n x A l 1 - x N is a prerequisite for their applications as a buffer layer. ispartof: JOURNAL OF APPLIED PHYSICS vol:125 issue:10 status: published
Published: 2019
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23. Structural investigation of InGaN/GaN heterostructures and quantum wells for long wavelength emission (Conference Presentation)

Author: Pierre Ruterana
Subjects: Long wavelength, Presentation, Materials science, business.industry, media_common.quotation_subject, Optoelectronics, Heterojunction, business, Quantum well, media_common
Published: 2019
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24. Effect of Cu doping on the structure and phase transition of directly synthesized FePt nanoparticles

Author: Yang Li, Dan Shu, Jun Zhang, Xu Chen, Hanbin Wang, Yi Wang, Pierre Ruterana, Xina Wang, Hao Wang, Xiang Liu, Innovation Center for Advanced Organic Chemical Materials (ICAOCM), Hubei University, Stuttgart Center for Electron Microscopy, Max Planck Institute for Intelligent Systems, Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Max Planck Institute for Intelligent Systems [Tübingen], Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Phase transition, Materials science, [PHYS.PHYS]Physics [physics]/Physics [physics], Condensed matter physics, chemistry.chemical_element, Nanoparticle, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, Coercivity, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Copper, Electronic, Optical and Magnetic Materials, Grain growth, Transition metal, chemistry, Chemical engineering, Transmission electron microscopy, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, 0210 nano-technology, Ternary operation
Abstract: International audience; In this work, ternary Cu doped FePt nanoparticles were prepared in hexadecylamine at 320 °C by choosing FeCl2 as the Fe source. The experimental results showed that without Cu doping the as-prepared FePt nanoparticles possessed fcc structure and gradually exhibited typical fct diffraction peaks after increasing the Cu doping concentration. TEM images showed that the FePt nanoparticles had larger size and wider size distribution after introducing Cu additive. Magnetic property measurement showed that a coercivity of 4800 Oe was obtained when the composition of the ternary nanoparticles reached Fe35Pt45Cu20, in which the content of Fe+Cu was higher than Pt. The research indicates that Cu doping promotes the phase transition of FePt nanoparticles at temperature as low as 320 °C.
Published: 2017
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25. Implantation damage formation in a-, c- and m-plane GaN

Author: Ferdinand Scholz, Elke Wendler, Stephan Schwaiger, Norberto Catarino, Katharina Lorenz, Pierre Ruterana, Marie Pierre Chauvat, Andrés Redondo-Cubero, Eduardo Alves, Instituto de Plasmas e Fusão Nuclear [Lisboa] (IPFN), Instituto Superior Técnico, Universidade Técnica de Lisboa (IST), Institut für Festkörperphysik, Friedrich-Schiller-Universität = Friedrich Schiller University Jena [Jena, Germany], Departamento de Física Aplicada [UAM Madrid], Universidad Autónoma de Madrid (UAM), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institute of Optoelectronic (IO), University of Ulm (UUlm), Universidad Autonoma de Madrid (UAM), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Materials science, [PHYS.PHYS]Physics [physics]/Physics [physics], Polymers and Plastics, Metals and Alloys, Nanotechnology, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, 021001 nanoscience & nanotechnology, Rutherford backscattering spectrometry, Channelling, 01 natural sciences, Crystallographic defect, Molecular physics, Electronic, Optical and Magnetic Materials, Crystal, Ion implantation, Transmission electron microscopy, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, Ceramics and Composites, Radiation damage, Dislocation, 0210 nano-technology
Abstract: International audience; Epitaxial GaN layers with a-, c- and m-plane surface orientations were implanted with 300 keV Ar-ions at 15 K with fluences ranging from 2 × 1012 to 4 × 1016 at/cm2. Damage build-up proceeds in three steps separated by wide fluence regions where the maximum damage level, measured by in situ Rutherford Backscattering Spectrometry/Channelling, saturates. The three steps occur at similar fluences for the three crystal orientations and similar defect formation rates for the lowest fluences are observed. Surprisingly, the second saturation regime reveals a significantly lower damage level in a-plane layers while m- and c-plane samples suffer more than 4 times higher damage levels. The strong radiation resistance of a-plane GaN was attributed to very efficient dynamic annealing of point defects during the implantation even at 15 K. The migration and aggregation of point defects also lead to distinct defect microstructures as evidenced by transmission electron microscopy. Besides point defects and their clusters the dominant extended defects caused by implantation in c-plane GaN are basal stacking faults while dislocation loops are formed in a-plane material. m-plane GaN presents a mixture of planar defects and dislocation loops after implantation.
Published: 2017
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26. Study of phase separation in an InGaN alloy by electron energy loss spectroscopy in an aberration corrected monochromated scanning transmission electron microscope

Author: X. Wang, Pierre Ruterana, Toshihiro Aoki, Veerendra C. Angadi, Thomas Walther, Paolo Longo, University of Sheffield [Sheffield], Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research - Chinese Academy of Sciences, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), LeRoy Eyring Center for Solid State Science, Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), and Messing, G
Subjects: Materials science, Band gap, 02 engineering and technology, Electron, 01 natural sciences, Molecular physics, Optics, 0103 physical sciences, Scanning transmission electron microscopy, [CHIM.CRIS]Chemical Sciences/Cristallography, General Materials Science, Spectroscopy, ComputingMilieux_MISCELLANEOUS, Plasmon, 010302 applied physics, [PHYS.PHYS]Physics [physics]/Physics [physics], Scattering, business.industry, Mechanical Engineering, Electron energy loss spectroscopy, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Mechanics of Materials, Density of states, 0210 nano-technology, business
Abstract: Phase separation of InxGa1−xN into Ga-rich and In-rich regions has been studied by electron energy-loss spectroscopy (EELS) in a monochromated, aberration corrected scanning transmission electron microscope (STEM). We analyze the full spectral information contained in EELS of InGaN, combining for the first time studies of high-energy and low-energy ionization edges, plasmon, and valence losses. Elemental maps of the N K, In M4,5 and Ga L2,3 edges recorded by spectrum imaging at 100 kV reveal sub-nm fluctuations of the local indium content. The low energetic edges of Ga M4,5 and In N4,5 partially overlap with the plasmon peaks. Both have been fitted iteratively to a linear superimposition of reference spectra for GaN, InN, and InGaN, providing a direct measurement of phase separation at the nm-scale. Bandgap measurements are limited in real space by scattering delocalization rather than the electron beam size to ∼10 nm for small bandgaps, and their energetic accuracy by the method of fitting the onset of the joint density of states rather than energy resolution. For an In0.62Ga0.38N thin film we show that phase separation occurs on several length scales.
Published: 2016
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27. Hole localization energy of 1.18 eV in GaSb quantum dots embedded in GaP

Author: Xavier Wallart, Christophe Coinon, Pierre Ruterana, Yi Wang, Leo Bonato, Ludovic Desplanque, Dieter Bimberg, and Ismail Firat Arikan
Subjects: 010302 applied physics, Physics, Condensed matter physics, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Orders of magnitude (time), Transmission electron microscopy, Quantum dot, Atomic resolution, 0103 physical sciences, 0210 nano-technology, Ground state, Energy (signal processing), Wetting layer, Molecular beam epitaxy
Abstract: Self-organized GaSb quantum dots are embedded in GaP by molecular beam epitaxy and n+p-diodes are fabricated. The structure of the sample is investigated using transmission electron microscopy with atomic resolution. The presence of quantum dots on top of a wetting layer and interdiffusion processes between Sb and P are observed. The localization energy, capture cross-section, and storage time of holes in the ground state of the quantum dots are determined via deep-level transient spectroscopy. Their localization energy of 1.18(±0.01)eV is found to agree with the theoretical prediction of 1.4 eV once the observed interdiffusion is taken into account. A storage time of holes of 3.9(±0.3) days at room temperature is calculated, marking an improvement of 3 orders of magnitude from previous record figures. GaSb/GaP quantum dots are, thus, promising candidates for future non-volatile DRAMs or fast Flash. Schematic representation of the quantum dots (left) and of the valence band in their vicinity (right). The localization energy is marked on the scheme. The localization of the quantum dots prevents thermal emission of holes, generating a storage time at room temperature of 3.9 days.
Published: 2016
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28. Investigation of phase separation in InGaN alloys by plasmon loss spectroscopy in a TEM

Author: Thomas Walther, M. P. Chauvat, X. Wang, and Pierre Ruterana
Subjects: 010302 applied physics, Range (particle radiation), Materials science, Mechanical Engineering, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Electron, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Molecular physics, Spectral line, chemistry, Mechanics of Materials, Transmission electron microscopy, 0103 physical sciences, General Materials Science, Thin film, 0210 nano-technology, Spectroscopy, Indium, Plasmon
Abstract: Phase separation of InxGa1-xN alloys into Ga-rich and In-rich regions was observed by a number of research groups for samples grown with high indium content, x. Due to the radiation sensitivity of InGaN to beam damage by fast electrons, high-resolution imaging in transmission electron microscopy (TEM) or core-loss electron energy-loss spectroscopy (EELS) may lead to erroneous results. Low-loss EELS can yield spectra of the plasmon loss regions at much lower electron fluxes. Unfortunately, due to their delayed edge onset, the low energetic core losses of Ga and In partially overlap with the plasmon peaks, all of which shift with indium content. Here we demonstrate a method to quantify phase separation in InGaN thin films from the low-loss region in EELS by simultaneously fitting both plasmon and core losses over the energy range of 13-30eV. Phase separation is shown to lead to a broadening of the plasmon peak and the overlapping core losses, resulting in an unreliable determination of the indium concentration from analyzing the plasmon peak position alone if phase separation is present. For x=0.3 and x=0.59, the relative contributions of the binary compounds are negligibly small and indicate random alloys. For x nom.=0.62 we observed strong broadening, indicating phase separation.
Published: 2016
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29. Core/shell Cu/FePtCu nanoparticles with face-centered tetragonal texture: An active and stable low-Pt catalyst for enhanced oxygen reduction

Author: Hanbin Wang, Hao Wang, Pierre Ruterana, Tianci Wu, Laifa Shen, Yi Wang, Xu Chen, Dan Shu, Peter Lund, Houzhao Wan, Faculty of Physics and Electronic Science (PES), Hubei University of Science and Technology, Max Planck Institute for Solid State Research, Max-Planck-Gesellschaft, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Department of Applied Physics [Aalto], Aalto University, Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Alloy, ta221, Face-centered tetragonal, Nanoparticle, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, 7. Clean energy, Catalysis, Oxygen reduction reaction, Tetragonal crystal system, Phase (matter), Scanning transmission electron microscopy, [CHIM.CRIS]Chemical Sciences/Cristallography, General Materials Science, Texture (crystalline), Electrical and Electronic Engineering, FePtCu, ta114, [PHYS.PHYS]Physics [physics]/Physics [physics], Renewable Energy, Sustainability and the Environment, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Core–shell structure, 0104 chemical sciences, Activity, Nanocrystal, Chemical engineering, engineering, 0210 nano-technology, Stability
Abstract: International audience; Low-Pt based nanocrystals demonstrate potential as highly active catalysts for the oxygen reduction reaction (ORR), but they suffer from undesirable structural degradation. Therefore, it is highly challenging to optimize their surface and interfacial structures to tune their catalytic properties for both activity and stability. Here core–shell Cu/FePtCu nanoparticles with a face-centered-tetragonal phase are prepared by a facile one–pot polyol method at 320 °C. The optimized core–shell Fe45Pt35Cu20 catalyst with Pt-enriched surface exhibits 0.5 A/mgPt mass activity, which is a factor of 4 better than that of commercial Pt/C (0.13 A/mgPt). In addition, the current density of the catalyst drops only 3.0% after 1000 cycles, which is much better than Pt/C (34.2% decay). Using aberration-corrected scanning transmission electron microscopy and atomically resolved elemental mapping, the morphology and structure evolving between the FePtCu alloy and core–shell Cu/FePtCu could clearly be explained. This work demonstrates that an ordered and core–shell FePtCu catalyst is highly promising for ORR and other electrochemical processes.
Published: 2018
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30. Generation of hole gas in non-inverted InAl(Ga)N/GaN heterostructures

Author: Farah Bouazzaoui, M. Veselý, Prerna Chauhan, M. P. Chauvat, Ľubomír Vančo, Stanislav Hasenöhrl, Pierre Ruterana, Roman Stoklas, Edmund Dobročka, Jan Kuzmik, Slovak Academy of Sciences (SAS), Slovak University of Technology in Bratislava, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Materials science, [PHYS.PHYS]Physics [physics]/Physics [physics], business.industry, Transistor, General Engineering, General Physics and Astronomy, Heterojunction, 02 engineering and technology, Chemical vapor deposition, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, law, Free electron density, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, Optoelectronics, 0210 nano-technology, business
Abstract: International audience; InAlN/GaN structures are grown using organometallic chemical vapor deposition at 730 °C. The sample for which the chamber cleaning step was applied after GaN growth shows a sharp In0.3Al0.7N/GaN transition, free electron density of ~2 × 1011 cm−2 and mobility of 44 cm2 V−1 s−1. On the other hand, the sample prepared without growth interruption demonstrated In0.4Al0.15Ga0.45N at the interface and compositional grading towards the In0.4Al0.6N surface. In this case a two-dimensional hole gas (2DHG) is created with a density of ~2 × 1012 cm−2 and mobility of ~0.6 cm2 V−1 s−1. Ga incorporation in the InAlN barrier is crucial for designing non-inverted 2DHG transistors.
Published: 2018
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31. Structural stability and electronic properties of the (0 0 0 1) inversion domain boundary in III-nitrides

Author: Pierre Ruterana, Pierre-Matthieu Anglade, Huaping Lei, Jun Chen, Siqian Li, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, General Computer Science, Population, General Physics and Astronomy, 02 engineering and technology, Electron, 01 natural sciences, symbols.namesake, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, General Materials Science, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, education, 010302 applied physics, education.field_of_study, Condensed matter physics, [PHYS.PHYS]Physics [physics]/Physics [physics], Fermi level, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Electron localization function, Computational Mathematics, Mechanics of Materials, Structural stability, Density of states, symbols, Density functional theory, 0210 nano-technology, Fermi gas
Abstract: International audience; A structural investigation of (0 0 0 1) plane inversion domain boundaries (IDBs) in group III-nitrides (GaN, AlN and InN) has been carried out by means of Monte Carlo (MC) simulation of Stillinger-Weber empirical potential. Eight possible IDB configurations were found to be stable during the structural searching process. Their energetics, chemical bonding properties as well as electronic structures were further investigated using first-principle calculations based on density functional theory (DFT). The comparison of relative energetic stability revealed that the H4 configuration is the most stable structure among H (Head-to-Head type) IDBs except in AlN; as for T (Tail-to-Tail type) IDBs, T2 is more energetic favorable within all materials. The electron localization function (ELF) and the Bader population analysis clearly point out 2-dimensional hole gas (2DHG) in H IDBs and 2-dimensional electron gas (2DEG) in T IDBs. And this is ascribed to the polarization discontinuity. A detailed analysis of Projected Density of States (PDOS) shows a metallic character in all IDBs. The hybridization states at the valance band edge crossed the Fermi level in H boundaries which acts as a p dopant. For T type IDBs, the PDOS is largely extended in density with the Fermi level shifted up above the conduction band maximum (CBM) which suggests an electron excess in boundaries.
Published: 2018
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32. Polarity Control within One Monolayer at ZnO/GaN Heterointerface: (0001) Plane Inversion Domain Boundary

Author: Ümit Özgür, Pierre Ruterana, Barkat Ullah, Huaping Lei, Yi Wang, Siqian Li, Hadis Morkoç, Vitaliy Avrutin, Jun Chen, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Max Planck Institute for Solid State Research, Max-Planck-Gesellschaft, Electrical and Computer Engineering (ECE), Virginia Commonwealth University (VCU), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Materials science, Condensed matter physics, [PHYS.PHYS]Physics [physics]/Physics [physics], business.industry, Heterojunction, 02 engineering and technology, Electronic structure, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Piezoelectricity, Pyroelectricity, Condensed Matter::Materials Science, Semiconductor, Octahedron, Transmission electron microscopy, 0103 physical sciences, Monolayer, [CHIM.CRIS]Chemical Sciences/Cristallography, General Materials Science, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0210 nano-technology, business
Abstract: International audience; In semiconductor heterojunction, polarity critically governs the physical properties, with an impact on electronic or optoelectronic devices through the presence of pyroelectric and piezoelectric fields at the active heteropolar interface. In the present work, the abrupt O-polar ZnO/Ga-polar GaN heterointerface was successfully achieved by using high O/Zn ratio flux during the ZnO nucleation growth. Atomic-resolution high-angle annular dark-field and bright-field transmission electron microscopy observation revealed that this polarity inversion confines within one monolayer by forming the (0001) plane inversion domain boundary (IDB) at the ZnO/GaN heterointerface. Through theoretical calculation and topology analysis, the geometry of this IDB was determined to possess an octahedral Ga atomic layer in the interface, with one O/N layer symmetrically bonded at the tetrahedral site. The computed electronic structure of all considered IDBs revealed a metallic character at the heterointerface. More interestingly, the presence of two-dimensional (2D) hole gas (2DHG) or 2D electron gas (2DEG) is uncovered by investigating the chemical bonding and charge transfer at the heterointerface. This work not only clarifies the polarity control and interfacial configuration of the O-polar ZnO/Ga-polar GaN heterojunction but, more importantly, also gives insight into their further application on heterojunction field-effect transistors as well as hybrid ZnO/GaN optoelectronic devices. Moreover, such polarity control at the monolayer scale might have practical implications for heterojunction devices based on other polar semiconductors.
Published: 2018
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33. A Theoretical Investigation of the Miscibility and Structural Properties of In x Al y Ga 1−x−y N Alloys

Author: Piero Gamarra, A. Béré, Ranim Mohamad, Pierre Ruterana, J. Chen, Viwanou Hounkpati, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université Ouaga (Université Ouaga), Université Joseph Ki-Zerbo [Ouagadougou] (UJZK), Alcatel-Thales III-V Lab (III-V Lab), THALES [France], Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Université Ouagadougou [Université Ouagadougou], and THALES
Subjects: 010302 applied physics, Spinodal, Materials science, [PHYS.PHYS]Physics [physics]/Physics [physics], Thermodynamics, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Enthalpy of mixing, 01 natural sciences, Miscibility, Electronic, Optical and Magnetic Materials, 0103 physical sciences, [CHIM.CRIS]Chemical Sciences/Cristallography, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0210 nano-technology, Phase diagram
Abstract: International audience; In this theoretical investigation of the miscibility in quaternary alloys, we stay in the regular solution model and determine the interaction parameters from the enthalpy of mixing calculated using a modified Stillinger–Weber (SW) potential for III‐nitride ternary alloys. From our calculation, the values of the interaction parameters are 6.605, 10.523, and 0.677 kcal mol−1, respectively, for InGaN, InAlN, and AlGaN at x = 0.5 (where x is the In and Al fraction in InGaN, InAlN, and AlGaN, respectively). These values are in good agreement with those predicted by the improved delta lattice parameter (DLP) model for nitride ternary alloys. To determine the unstable regions characterized by the spinodal decomposition of the quaternary alloy InxAlyGa1−x−yN, we consider the composition ranges of 0.06 ≤ x ≤ 1 and 0 ≤ y ≤ 0.94. Our calculations show that the phase separation temperature increases with the increase of indium concentration. For In concentration lower than 9.4%, the quaternary alloy is miscible independent of the Al and Ga compositions in the usual growth temperature range for metalorganic vapor phase epitaxy.
Published: 2018
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34. Probing the Local Electrical Properties of Al(In,Ga)N by Kelvin Probe Force Microscopy

Author: Ana Cros, Albert Minj, Pierre Ruterana, Hichem Ben Ammar, Núria Garro, Piero Gamarra, Sylvain Delage, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Institut Universitari de Ciencia dels Materials (ICMUV), Universitat de València (UV), Alcatel-Thales III-V Lab (III-V Lab), THALES, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), and THALES [France]
Subjects: 010302 applied physics, Coalescence (physics), Kelvin probe force microscope, Materials science, Condensed matter physics, Deep level, [PHYS.PHYS]Physics [physics]/Physics [physics], Surface photovoltage, chemistry.chemical_element, 02 engineering and technology, Electron, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, chemistry, 0103 physical sciences, Microscopy, [CHIM.CRIS]Chemical Sciences/Cristallography, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0210 nano-technology, Indium, Hillock
Abstract: International audience; In this work, local electrical properties of the crystallographic defects including V‐defects and trenches in ternary alloy AlGaN and quaternary alloys Al(Ga,In)N with different indium concentration are studied by light‐assisted Kelvin probe force microscopy. This surface sensitive technique is used to reveal the role of these defects as deep level electron traps. The evolution of topography of the layers from AlGaN to indium‐containing alloys is also investigated; it highlights the transformation of step‐flow to three‐dimensional growth mode. It is also shown that at the coalescence boundaries of growth hillocks, defects are generated which act as electrically active electron traps.
Published: 2018
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35. Energetic and Electronic Properties of (0001) Inversion Domain Boundaries in ZnO

Author: Jun Chen, Pierre Ruterana, Siqian Li, Huaping Lei, Zhuo Wang, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, State Key Laboratory of Chemical Resource Engineering, College of Science, Beijing University of Chemical Technology, Beijing, Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010302 applied physics, Materials science, [PHYS.PHYS]Physics [physics]/Physics [physics], Inversion (meteorology), 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electron localization function, Electronic, Optical and Magnetic Materials, Computational physics, 0103 physical sciences, Density of states, [CHIM.CRIS]Chemical Sciences/Cristallography, Density functional theory, 0210 nano-technology, Electronic properties
Abstract: International audience; In this work, the eight possible configurations of (0001) inversion domain boundaries (IDBs) in wurtzite ZnO have been investigated systematically by first‐principle calculations based on density‐functional theory (DFT). The energetic stability revealed that H4 are the most stable among the Head‐to‐Head type (H) IDBs, whereas for the Tail‐to‐Tail type (T) IDBs, T1 and T2 IDBs have lower formation energies. Their electronic properties were investigated using the electron localization function (ELF) and the projected density of states (PDOS). The results revealed that all the boundaries present a metallic character with the hybridization bands crossing the Fermi level; they are mainly dominated by Zn:3d and O:2p states in H IDBs and Zn:4s states in T IDBs, respectively. In particular, owing to the polarization discontinuity, electron accumulation occurs at all the T IDB regions with the conduction band minimum (CBM) shifting down below the Fermi level.
Published: 2018
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36. Internal quantum efficiency in polar and semipolar (11e22) InxGa1-xN/InyGa1-yN quantum wells emitting from blue to red

Author: Benjamin Damilano, Pierre Valvin, Philippe De Mierry, Thi Huong Ngo, Bernard Gil, Nicolas Chery, Aimeric Courville, Pierre Ruterana, Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Nanostructures quantiques propriétés optiques (NQPO), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Physique de l'Exciton, du Photon et du Spin (PEPS), Centre de recherche sur l'hétéroepitaxie et ses applications (CRHEA), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), ANR-11-LABX-0014,GANEX,Réseau national sur GaN(2011), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), and Université Nice Sophia Antipolis (... - 2019) (UNS)
Subjects: 010302 applied physics, Photoluminescence, Materials science, Condensed matter physics, Quantum-confined Stark effect, chemistry.chemical_element, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Molecular physics, Photoexcitation, Condensed Matter::Materials Science, chemistry, Electric field, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, Quantum efficiency, Electrical and Electronic Engineering, 0210 nano-technology, Spectroscopy, Indium, Quantum well
Abstract: International audience; In this work, we investigate the impact of the quantum confined Stark effect and of the carrier localization on the internal quantum efficiency of polarized single or multiple InxGa1-xN/GaN quantum well(s), and semi-polar (11e22) multiple InxGa1-xN/InyGa1-yN quantum well. We find that increasing the influence of the quantum confined Stark effect at constant indium content with increasing the well-width induces a reduction of the internal quantum efficiency onsets for a decreasing value of the photoexcitation density. Similar but no so dramatic trend is reported when increasing the indium content and thus when increasing the localization of carriers to localized fluctuations of the chemical composition of the alloy. In addition, a change of the electric field internal to active layers (quantified by using time-resolved photoluminescence spectroscopy) realized by growing samples along a semi-polar orientation leads to experimental observation of a substantial enhancement of the threshold of photoexcitation density at which onsets the reduction of the internal quantum efficiency. A correlation is found through several orders of magni- tude between the photoexcitation density PT for the onset of the collapse of IQE and the values of the photoluminescence radiative decay time trad. A scaling law is found in the investigated samples: PT ~ trad-n with n 1⁄4 3/2 ± 0.15 which evidences that quantum confined Stark effect is the main origin for the efficiency droop in nitride light-emitting diodes based on InxGa1-xN active layers.
Published: 2018
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37. Mechanisms for the formation of inversion domains in GaN

Author: G P Dimitrakopoulos, Ana M. Sanchez, and Pierre Ruterana
Subjects: Materials science, Geophysics, Inversion (discrete mathematics)
Published: 2018
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38. Analysis of [0001] tilt grain boundaries in GaN

Author: Pierre Ruterana, J Chen, and G Nouee
Subjects: Tilt (optics), Materials science, Grain boundary, Geometry
Published: 2018
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39. Structural Investigations in Nitride Semiconductors for Optoelectronic Applications

Author: Pierre Ruterana
Subjects: Materials science, business.industry, Optoelectronics, Nitride semiconductors, business
Published: 2017
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40. Single step hydrothermal synthesis of mixed valent V 6 O 13 nano-architectures: A case study of the possible applications in electrochemical energy conversion

Author: Pierre Ruterana, Jim Buckman, S. R. Popuri, Geeta Rani Mutta, School of Engineering and Physical Sciences [Edinburgh] (EPS-HWU), Heriot-Watt University [Edinburgh] (HWU), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Institute of Petroleum Engineering, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Auxiliary electrode, Materials science, Vanadium, chemistry.chemical_element, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, 7. Clean energy, Hydrothermal circulation, Vanadium oxide, Nano, Materials Chemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, Hydrothermal synthesis, [PHYS.PHYS]Physics [physics]/Physics [physics], Mechanical Engineering, Metals and Alloys, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Electrochemical energy conversion, 0104 chemical sciences, Dye-sensitized solar cell, chemistry, 13. Climate action, Mechanics of Materials, 0210 nano-technology
Abstract: International audience; Availability of several stable vanadium oxidation states offers numerous advantages in terms of applications but at the same time it poses great challenge to isolate them in single phase during their synthesis process. In this study, we developed a facile single step hydrothermal synthesis of V6O13 nano-architectures using environmental friendly citric acid as a reducing agent. By means of time dependant hydrothermal conditions study, we observed evolution of several stable vanadium oxide phases. The as-synthesized powder samples phase confirmation was thoroughly studied by powder X-ray diffraction and transmission electron microscopy. The morphology of the products formed was investigated at each hydrothermal reaction time. Finally, these V6O13 nano-architectures were employed as counter electrode (CE) in dye sensitized solar cells (DSSCs). The photovoltaic performance and the electrical impedance studies of the DSSC device made use of V6O13 nano-architectures are reported here. It is believed that with further optimization, this relatively inexpensive material can act as efficient CE for DSSCs, which thereby open up a new avenue for vanadium oxides as a new class of materials for clean energy generation.
Published: 2017
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41. Synthesis and characterization of nanocomposites films with graphene oxide and reduced graphene oxide nanosheets

Author: Christophe Poilâne, Meryem Goumri, Pierre Ruterana, Bessem Ben Doudou, Jany Wéry, Anass Bakour, Mimouna Baitoul, Université libre de Bruxelles (ULB), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique du solide [Université Sidi Mohamed Ben Abdellah, Fès] | Laboratory of Solid-State Physics (LPS), Faculté des Sciences Dhar Mehraz, Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), Laboratory of Solid State Physics Fes, Maroc, Sidi Mohammed Ben Abdellah University, Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), and Normandie Université (NU)
Subjects: Vinyl alcohol, Thermogravimetric analysis, Materials science, Nanocomposite, Graphene, Oxide, General Physics and Astronomy, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Exfoliation joint, 0104 chemical sciences, law.invention, chemistry.chemical_compound, Differential scanning calorimetry, chemistry, Chemical engineering, law, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Graphene oxide paper
Abstract: Graphene oxide (GO) and reduced graphene oxide (CRGO), as a graphene derivatives, possess unique properties and a high aspect ratio, indicating great potential in nanocomposite fields. The present work reports the fabrication of the nanocomposite films by a simple and environmentally friendly process using aqueous solution and optimized time sonication for better exfoliation of the graphene sheets within Poly(Vinyl alcohol) (PVA) as matrix. The films were characterized using high-resolution TEM (HRTEM), X-ray diffraction (XRD), Microtensile testing, Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA). The TEM images revealed a successfully exfoliation of the GO/CRGO nanosheets. XRD combined with TGA and DSC measurements showed an improvement in the thermal stability and tunable thermal properties. In addition, the Young's modulus and tensile yield strength of the composite films containing 1 wt% GO were obtained to be 4.92 GPa and 66 MPa respectively. These excellent reinforcement effects were achieved by the strong interaction between the components.
Published: 2017
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42. Positron energy levels in zinc chalcogenides ZnS, ZnSe, and ZnTe

Author: B. Bouhafs, B. Abbar, Pierre Ruterana, F. Benosman, S. Méçabih, and N. Benosman
Subjects: General Computer Science, business.industry, General Physics and Astronomy, chemistry.chemical_element, General Chemistry, Zinc, Electron, Positron energy, Positronium, Condensed Matter::Materials Science, Computational Mathematics, Formalism (philosophy of mathematics), Delocalized electron, Positron, Semiconductor, chemistry, Mechanics of Materials, Physics::Accelerator Physics, General Materials Science, Atomic physics, business
Abstract: The self-consistent electron densities and the corresponding positron states are calculated for the zinc chalcogenides, ZnS, ZnSe and ZnTe, in the local-density approximation of the density-functional formalism. The calculations are performed with the full-potential linearized augmented plane-wave (FP-LAPW) method. The emphasis of this work is on the energy levels of the delocalized positron and the electron chemical potential. These energies determine quantities such as the positron and positronium work functions and the deformation potentials which are important parameters in slow-positron-beam experiments.
Published: 2014
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43. Half metallic properties of the quaternary CuFe2GaSe4 chalcogenide compound

Author: S. Medina, B. Bouhafs, and Pierre Ruterana
Subjects: General Computer Science, Magnetic moment, Spintronics, Condensed matter physics, Magnetism, Chemistry, General Physics and Astronomy, General Chemistry, Condensed Matter::Materials Science, Computational Mathematics, Tetragonal crystal system, Atomic orbital, Mechanics of Materials, Condensed Matter::Strongly Correlated Electrons, General Materials Science, Direct and indirect band gaps, Density functional theory, Half-metal
Abstract: The structural, electronic and magnetic properties of quaternary CuFe2GaSe4 in stannite structure (tetragonal structure, space group I 4 ¯ 2 m ) were investigated using the full potential augmented plane wave plus local orbitals method based on density functional theory. For exchange–correlation potential, the local spin density approximation LSDA and LSDA+U schemes were adopted. It is shown that the application of the Coulomb interaction U increases the lattice parameters relative to the LSDA approach. The analysis of the densities of states shows that this compound is semiconductor and metallic in the majority and minority spin channels, respectively. This half metallicity of the majority spin exhibits a direct band gap of Eg = 0.62 eV, and a magnetic moment of 8 μB. The magnetism comes from the d orbitals of Fe atoms and the p-Se, d-Fe coupling. These results may be of interest for spintronic applications.
Published: 2014
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44. First-principles calculations of the elastic, and electronic properties of YFe2, NiFe2 and YNiFe4 intermetallic compounds

Author: Ali H. Reshak, S. Benalia, N. Benkhettou, Pierre Ruterana, M. Rabah, Djamel Rached, N. Moulay, and Habib Rached
Subjects: Materials science, General Computer Science, Magnetic moment, Condensed matter physics, Fermi level, Intermetallic, General Physics and Astronomy, General Chemistry, Shear modulus, Computational Mathematics, symbols.namesake, Lattice constant, Mechanics of Materials, Atom, symbols, General Materials Science, Local-density approximation, Debye model
Abstract: Based on first principles full potential linear muffin-tin orbital method within the local density approximation, we have studied the structural, elastic, electronic properties and the behaviour under pressure on the magnetic moments per atoms from 0 to 85 GPa for YFe2, NiFe2 and YNiFe4 intermetallic. The magnetic per formula unit value and equilibrium lattice constant of YFe2 are calculated and compared with experimental data and theoretical results. However, this is the first predictive calculations for the structural and magnetic properties for NiFe2 and YNiFe4 compounds. From the computed elastic constants, theoretical value of Young’s modulus, Shear modulus, Poisson’s ratio and Lame’s coefficients, sound velocities and Debye temperature are evaluated. Our results demonstrate that NiFe2, YFe2 in C15 phase and NiYFe4 in C15b phase are mechanically stable with the large bulk moduli B0 = BVR for alloys containing atom Ni (NiFe2 = 224.7 GPa and NiYFe4 = 192.0 GPa). Finally, we have calculated the total and partial density of states for the three compounds. The partial density of states shows strong hybridization at Fermi level.
Published: 2013
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45. Electrical properties of extended defects in III-nitrides

Author: Pierre Ruterana, Daniela Cavalcoli, Albert Minj, Arantxa Vilalta-Clemente, Geeta Rani Mutta Popuri, Anna Cavallini, Albert Minj, Daniela Cavalcoli, Geeta Rani Mutta Popuri, Arantxa Vilalta-Clemente, Pierre Ruterana, and Anna Cavallini
Subjects: Kelvin probe force microscope, Materials science, Polymers and Plastics, Condensed matter physics, Electron beam-induced current, Doping, III-Nitride, Metals and Alloys, chemistry.chemical_element, Heterojunction, Condutive AFM, extended defects, Electric charge, Electronic, Optical and Magnetic Materials, Crystallography, chemistry, Transmission electron microscopy, Microscopy, Ceramics and Composites, Indium
Abstract: Electrical and structural properties of extended defects including threading dislocations/V-defects and nanopipes in unintentionally doped GaN, InGaN (50 nm)/GaN and AlInN (33 nm)/AlN(1 nm)/GaN heterostructures have been investigated by means of various scanning probe (Kelvin probe and conductive-Atomic Force Microscopy) and electron beam (electron beam induced current and transmission electron microscopy) microscopy methods. Due to low energy measurements of Kelvin probe force microscopy, charge state of the dislocations have been correctly identified where threading dislocations (TDs) with screw-component are negatively charged, while pure-edge type TDs are neutral in InGaN/GaN. It is explained how various factors such as indium segregation, surface termination, presence of vacancies and/or impurities affect the electrical charge, conductivity and recombination properties of the extended defects. They are found to be strongly correlated to the type of dislocations as identified from TEM.
Published: 2015

46. Direct one-pot synthesis of L1 0 –FePtAg nanoparticles with uniform and very small particle sizes

Author: Xu Chen, Yi Wang, Hanbin Wang, Jun Zhang, Dan Shu, Pierre Ruterana, Hao Wang, Shanghai Academy of Agricultural Sciences, Laboratoire de Mécanique de Lille - FRE 3723 (LML), Université de Lille, Sciences et Technologies-Centrale Lille-Centre National de la Recherche Scientifique (CNRS), Polymères Biopolymères Surfaces (PBS), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Institut Normand de Chimie Moléculaire Médicinale et Macromoléculaire (INC3M), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Microbiology, Wageningen University and Research [Wageningen] (WUR), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Tianjin Agricultural University (TJAU), Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Institut Normand de Chimie Moléculaire Médicinale et Macromoléculaire (INC3M), Institut de Chimie du CNRS (INC)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Université de Lille, Sciences et Technologies-Ecole Centrale de Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, [PHYS.PHYS]Physics [physics]/Physics [physics], Magnetism, Nucleation, Nanoparticle, Nanotechnology, 02 engineering and technology, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, Coercivity, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Solvent, Tetragonal crystal system, Chemical engineering, Phase (matter), Materials Chemistry, [CHIM.CRIS]Chemical Sciences/Cristallography, Solvent effects, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract: If tetragonal FePt nanoparticles (NPs) are to be used as magnetic recording media, a means of transforming the particles into the tetragonal phase while maintaining the small particle size must be found. In this work, uniform and high coercivity L10–FePtAg nanoparticles are successfully synthesized by a one-pot polyol-process method, using an octadecylamine solvent. Magnetic measurements show that FePtAg NPs with a high coercivity of 5.23 kOe can be achieved using the octadecylamine solvent, which is significantly higher than the NPs synthesized using hexadecylamine (2.84 kOe) and trioctylamine (2.81 kOe) solvents. STEM characterization shows that the L10–FePtAg NPs synthesized in octadecylamine, with a diameter of 3.5 ± 0.5 nm and a very uniform size distribution, are smaller in size and more uniform than those synthesized in hexadecylamine and trioctylamine solvents. The octadecylamine, hexadecylamine and trioctylamine high boiling-temperature solvents play significant roles in the morphology, structure and magnetism of FePtAg NPs, and the solvent effects on the nucleation and growth of the L10–FePtAg nanoparticles are proposed. This work sheds new light on designing highly ordered L10–FePt nanoparticles for ultrahigh density magnetic recording and for synthesising high performance oxygen reduction reaction catalysts.
Published: 2017
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47. InAlGaN/GaN HEMTs at Cryogenic Temperatures

Author: Cedric Lacam, Sylvie Lepilliet, M. P. Chauvat, Astrid Linge, M. Tordjman, Farid Medjdoub, Ezgi Dogmus, Pierre Ruterana, Malek Zegaoui, Riad Kabouche, Piero Gamarra, Hichem Ben-Ammar, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Thales Research and Technology [Palaiseau], and THALES [France]
Subjects: Power gain, Electron mobility, Materials science, Computer Networks and Communications, lcsh:TK7800-8360, 02 engineering and technology, 01 natural sciences, 7. Clean energy, [SPI]Engineering Sciences [physics], 0103 physical sciences, Electrical and Electronic Engineering, Sheet resistance, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, InAlGaN HEMT, cryogenic temperature, microwave, business.industry, lcsh:Electronics, Direct current, Heterojunction, Cryogenic temperature, 021001 nanoscience & nanotechnology, Hardware and Architecture, Control and Systems Engineering, Signal Processing, Optoelectronics, Radio frequency, 0210 nano-technology, Fermi gas, business, Microwave
Abstract: International audience; We report on the electron transport properties of two-dimensional electron gas confined in a quaternary barrier InAlGaN/AlN/GaN heterostructure down to cryogenic temperatures for the first time. A state-of-the-art electron mobility of 7340 cm2·V−1·s−1 combined with a sheet carrier density of 1.93 × 1013 cm−2 leading to a remarkably low sheet resistance of 44 Ω/□ are measured at 4 K. A strong improvement of Direct current (DC) and Radio frequency (RF) characteristics is observed at low temperatures. The excellent current and power gain cutoff frequencies (fT/fmax) of 65/180 GHz and 95/265 GHz at room temperature and 77 K, respectively, using a 0.12 μm technology confirmed the outstanding 2DEG properties.
Published: 2016
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48. P-i-n InGaN homojunctions (10-40% In) synthesized by plasma-assisted molecular beam epitaxy with extended photoresponse to 600 nm

Author: Eva Monroy, S. Valdueza-Felip, T. Cremel, Luca Redaelli, K. Kheng, M. Jiménez-Rodríguez, Marie Pierre Chauvat, Akhil Ajay, Pierre Ruterana, Nanophysique et Semiconducteurs (NPSC), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), 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), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Universidad de Alcalá - University of Alcalá (UAH), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, FOS: Physical sciences, 02 engineering and technology, Epitaxy, Mole fraction, 01 natural sciences, law.invention, law, 0103 physical sciences, Solar cell, Homojunction, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 010302 applied physics, Condensed Matter - Materials Science, Renewable Energy, Sustainability and the Environment, business.industry, Materials Science (cond-mat.mtrl-sci), Heterojunction, 021001 nanoscience & nanotechnology, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, Quantum efficiency, 0210 nano-technology, business, Molecular beam epitaxy, Stacking fault
Abstract: International audience; We report the influence of the In mole fraction on the material and electrical characteristics of p-i-n InxGa1−xN homojunctions (x=0.10–0.40) synthesized by plasma-assisted molecular-beam epitaxy on GaN-on-sapphire substrates. Junctions terminated with p-InGaN present improved carrier extraction efficiency in comparison with devices capped with p-GaN, due to the deleterious effect of polarization discontinuities on the device performance. We demonstrate that the presence of Mg does not perturb the In incorporation in InGaN, and it leads to a significant reduction of the stacking fault density. p-In0.3Ga0.7N layers with a hole concentration of 3.2×1018 cm−3 are demonstrated. InGaN homojunction devices show a peak EQE=14±2% in the blue-to-orange spectral region, and an extended cutoff to 600 nm.
Published: 2016
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49. Cover Picture: Polarity control and residual strain in ZnO epilayers grown by molecular beam epitaxy on (0001) GaN/sapphire (Phys. Status Solidi RRL 9/2016)

Author: Morteza Monavarian, Mykyta Toporkov, Si Qian Li, Vitaliy Avrutin, Saikat Das, Ümit Özgür, Hadis Morkoç, M. B. Ullah, and Pierre Ruterana
Subjects: Materials science, business.industry, Polarity (physics), Residual strain, Sapphire, Optoelectronics, General Materials Science, Cover (algebra), Condensed Matter Physics, business, Molecular beam epitaxy
Published: 2016
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50. Selective Area growth of GaSb nano-templates on GaAs (001) using atomic hydrogen assisted Molecular Beam Epitaxy

Author: Xavier Wallart, M Fahed, David Troadec, Pierre Ruterana, and Ludovic Desplanque
Subjects: Materials science, Hydrogen, business.industry, Nanowire, chemistry.chemical_element, Nanotechnology, Epitaxy, Gallium arsenide, chemistry.chemical_compound, Atomic layer deposition, chemistry, Nano, Atomic layer epitaxy, Optoelectronics, business, Molecular beam epitaxy
Abstract: We investigate the growth conditions for Selective Area Molecular Beam Epitaxy of GaSb on (001) GaAs inside SiO 2 nano-stripes. We show that the use of an atomic hydrogen flux during the growth promote selective epitaxy at low temperature where a few micron long GaSb nanowires can be obtained both in [110] and [110] orientation. Furthermore, we demonstrate that reducing the Sb/Ga flux ratio during growth leads to an improved GaSb relaxation along [110] and line continuity along [110].
Published: 2016
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