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1. Bringing atom probe tomography to transmission electron microscopes

Author

Gerald Da Costa, Celia Castro, Antoine Normand, Charly Vaudolon, Aidar Zakirov, Juan Macchi, Mohammed Ilhami, Kaveh Edalati, François Vurpillot, and Williams Lefebvre

Subjects
Science
Abstract

Abstract For the purpose of enhancing the structural insights within the three-dimensional composition fields revealed by atom probe tomography, correlative microscopy approaches, combining (scanning) transmission electron microscopy with atom probe tomography, have emerged and demonstrated their relevance. To push the boundaries further and facilitate a more comprehensive analysis of nanoscale matter by coupling numerous two- or three-dimensional datasets, there is an increasing interest in combining transmission electron microscopy and atom probe tomography into a unified instrument. This study presents the tangible outcome of an instrumental endeavour aimed at integrating atom probe tomography into a commercial transmission electron microscope. The resulting instrument demonstrates the feasibility of combining in situ 3D reconstructions of composition fields with the detailed structural analysis afforded by transmission electron microscopy. This study shows a promising approach for converging these two important nanoscale microscopy techniques.

Published
2024
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2. Effect of Nitrite and Temperature on Autotrophic Denitrification in Anammox Granular Biomass from a Partial Nitritation–Anammox Reactor

Author

Benjamín Ibarra, Yves Lesty, Mateo Pastur, Celia Castro, Chloe Girard, and Rolando Chamy

Subjects
anammox, nitrite, inhibition, temperature, kinetic, Fermentation industries. Beverages. Alcohol, TP500-660
Abstract

Anaerobic ammonium oxidation (anammox) is a key process in the removal of nitrogen from wastewater, in which episodes of substrate inhibition may occur. In this study, the effect of nitrite on anammox in the short and long term was investigated using granules from a full-scale SBR reactor in operation. In the short term, maximum activity was achieved at 100 mg N-NO2−/L, with higher concentrations being inhibitory. It was determined that the biomass behavior is well interpreted (R2 = 0.955) by a non-competitive substrate inhibition model (Andrews model), with a KS of 55.6 mg N-NO2−/L and a KI of 116.7 mg N-NO2−/L, and also well interpreted by the Edwards model (R2 = 0.957), with a KS of 36 mg N-NO2−/L and a KI of 287 mg N-NO2−/L. In the long term, the biomass retained its anammox activity at 15 mg N-NO2−/L over a three TRH horizon; however, at 30 mg N-NO2−/L, anammox activity decreased by 50% at the end of the experiment. Finally, the effect of temperature on the activity of the anammox granules from a different source was studied, revealing that the activity increases with temperature within the range of 25–35 °C, which can be useful if a rapid increase in activity is desired. Operationally, maintaining nitrite below 30 mg N-NO2−/L ensures stability, while exceeding 100 mg N-NO2−/L causes immediate SAA inhibition and slower recovery.

Published
2024
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4. Combined Electron Microscopy Approaches for Arterial Glycocalyx Visualization

Author

Laurence Chevalier, Jean Selim, Celia Castro, Fabien Cuvilly, Jean-Marc Baste, Vincent Richard, Philippe Pareige, and Jeremy Bellien

Subjects
endothelial glycocalyx, FIBSEM tomography, scanning transmission electron microscopy, scanning electron microsopy, ischemia-reperfusion, pulmonary artery, Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Mainly constituted of glycosaminoglycans and proteoglycans, the glycocalyx is anchored in the plasma membrane, covering, in particular, the extracellular face of the arterial endothelium. Due to its complex three-dimensional (3D) architecture, the glycocalyx interacts with a wide variety of proteins, contributing to vascular permeability, the flow of mechanotransduction, and the modulation of local inflammatory processes. Alterations of glycocalyx structure mediate the endothelial dysfunction and contribute to the aggravation of peripheral vascular diseases. Therefore, the exploration of its ultrastructure becomes a priority to evaluate the degree of injury under physiopathological conditions and to assess the impact of therapeutic approaches. The objective of this study was to develop innovative approaches in electron microscopy to visualize the glycocalyx at the subcellular scale. Intravenous perfusion on rats with a fixing solution containing aldehyde fixatives enriched with lanthanum ions was performed to prepare arterial samples. The addition of lanthanum nitrate in the fixing solution allowed the enhancement of the staining of the glycocalyx for transmission electron microscopy (TEM) and to detect elastic and inelastic scattered electrons, providing complementary qualitative information. The strength of scanning electron microscopy (SEM) was used on resin-embedded serial sections, allowing rapid and efficient large field imaging and previous correlative TEM observations for ultrastructural fine details. To demonstrate the dynamic feature of the glycocalyx, 3D tomography was provided by dual-beam focus-ion-beam-SEM (FIB-SEM). These approaches allowed us to visualize and characterize the ultrastructure of the pulmonary artery glycocalyx under physiological conditions and in a rat pulmonary ischemia-reperfusion model, known to induce endothelial dysfunction. This study demonstrates the feasibility of combined SEM, TEM, and FIB-SEM tomography approaches on the same sample as the multiscale visualization and the identification of structural indicators of arterial endothelial glycocalyx integrity.

Published
2022
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5. Forma Aberta: a proposta de Oskar Hansen e Svein Hatloy para o PREVI — Proyecto Experimental de Vivienda — Peru

Author

Celia Castro-Gonsales and Gabriel Alvariz-Lopes

Subjects
habitação social, PREVI, revisão do modernismo, Forma Aberta, habitação flexível, Architecture, NA1-9428
Abstract

O concurso para o conjunto habitacional do PREVI (Proyecto Experimental de Vivienda), realizado em 1969, em Lima, se deu em um momento especialmente fértil de reflexões sobre as transformações da arquitetura e, principalmente, das cidades. Nesse contexto de crítica, temas como a participação cidadã e a transformação da arquitetura no tempo tornaram-se centrais e influíram decisivamente nas propostas das 13 equipes internacionais que participaram do concurso no Peru. Esse laboratório projetual, promovido pelo governo peruano com financiamento da ONU, tornou-se, na visão dos autores deste artigo, uma experiência fundamental em habitação social na América Latina no século XX, concentrando projetos seminais cujas ideias reverberam ainda hoje. Se todas as equipes internacionais convidadas a participar do concurso já tinham, naquele momento, um significativo repertório no tema da habitação e estavam em grande sintonia com a produção crítica de seus contemporâneos, a equipe polonesa, composta por Oskar Hansen e Svein Hatloy, trazia para o Peru uma bagagem de trabalho muito particular que vinha desenvolvendo no leste europeu. Dois conceitos estruturantes da produção prática e teórica de Oskar Hansen e de sua esposa, Zofia Hansen — a “Forma Aberta” e o seu desdobramento em escala urbana, o “Sistema Linear Contínuo” (SLC) — aparecem na proposta para o PREVI como instrumentos na busca por uma arquitetura flexível no espaço e no tempo, aberta à participação e intervenção do morador e adequada às suas particularidades socioculturais. Desse modo, o presente artigo tem por objetivo resgatar, em um recorte mais específico, as ideias norteadoras da proposta polonesa para o concurso e, em sentido mais amplo, trazer à tona a importância do PREVI enquanto referência fundamental para projetos de habitação social na contemporaneidade.

Published
2022
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6. Complexo Habitacional Bulevar Artigas, Uruguai: proposta de cidade a partir da crítica do segundo pós-guerra

Author

Carolina Ritter and Celia Castro-Gonsales

Subjects
arquitectura social uruguaia, espaço urbano, movimiento moderno, projecto de habitação, teoria arquitectônica, Architecture, NA1-9428
Abstract

Inserido essencialmente no campo conceitual e projetual das cooperativas habitacionais uruguaias, este artigo tem como objetivo verificar de que modo e com que intensidade estão presentes as propostas do cenário crítico internacional dos anos 1950 e 1960, em relação à cidade funcionalista, nas estratégias projetuais do Complexo Habitacional Bulevar Artigas. Para este estudo, o cenário é protagonizado principalmente pelos grupos Team 10 e Metabolistas, e defende-se aqui que, em um contexto inicialmente positivo dado pelo sistema cooperativo, as reverberações dos princípios desses grupos foram de grande contribuição para o êxito desse conjunto em termos de apropriação dos espaços pelos moradores e de uma compreensão geral, por parte desses, de seu habitat. Os limites e potencialidades dessas propostas teóricas, assim como seu diálogo com a vida contemporânea, pôde ser verificado por meio da observação da “realidade” do conjunto habitacional, por parte das autoras.

Published
2022
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7. Analysis of the Continuous Feeding of Catalyst Particles during the Growth of Vertically Aligned Carbon Nanotubes by Aerosol-Assisted CCVD

Author

Celia Castro, Rodrigo Fernández-Pacheco, Mathieu Pinault, Odile Stephan, Cécile Reynaud, and Martine Mayne-L’Hermite

Subjects
carbon nanotubes, aerosol assisted CCVD, ferrocene, cobaltocene, EELS, WDS, Chemistry, QD1-999
Abstract

Aerosol-assisted catalytic chemical vapor deposition (AACCVD) is a powerful one-step process to produce vertically aligned carbon nanotubes (VACNTs), characterized by the continuous supply of the catalyst precursor (metallocene). The behavior of catalyst species all along the synthesis is essential for the continuous growth of VACNTs. It is there investigated through detailed observations and elemental analyses at scales of VACNT carpets and of individual CNTs. Our approach is based on two complementary experiments: quenching of the sample cooling, and sequential injection of two distinct metallocenes. Metal-based nanoparticles nucleated in the gas-phase during the whole synthesis duration are shown to diffuse in between the growing VACNTs from the top of the CNT carpet towards the substrate. They are much smaller than the catalyst particles formed on the substrate in the initial steps of the process and evidences are given that they continuously feed these catalyst particles at the VACNT roots. Particularly, the electron energy-loss spectroscopy (EELS) analyses of metal-based segments found into a single CNT show that the second injected metal is very gradually incorporated in the particle initially formed from the metal firstly injected. The feeding of the catalyst particles by the nanoparticles continuously nucleated in the gas-phase is therefore an essential feature of the base-growth of CNTs by AACCVD.

Published
2022
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10. HOMICÍDIOS NO RIO GRANDE DO NORTE E SUA RELAÇÃO COM A PANDEMIA DO COVID-19

Author

Celia Castro, Fabiane Holanda, Joadson Carvalho, José Barbosa, and Anna Gomes

Abstract

O estudo tem como objetivo analisar os homicídios no Estado do Rio Grande do Norte, no período da Pandemia da Covid-19.Utiliza-se para tal os dados dos seguintes órgãos: Secretaria de Estado da Segurança Pública e da Defesa Social do Rio Grande do Norte (Sesed), Instituto Brasileiro de Geografia e Estatística (IBGE), Laboratório de Inovação Tecnológica em Saúde (LAIS) e Instituto de Pesquisa Observatório da Violência (OBVIO). Com base nas informações coletadas observa-se que no estado do Rio Grande do Norte o número de assassinatos está crescendo em níveis superiores à evolução da população, que o número de homicídios regride com as medidas iniciais de isolamento e volta a aumentar com o relaxamento das medidas e que existe uma tendência ascendente entre as taxas de isolamento social e de homicídios. Relacionando 2019 a 2020 tem-se um aumento da quantidade de homicídios com a pandemia, sobretudo o homicídio doloso, sendo o maior número de mortes referente ao uso de armas de fogo e as principais vítimas crianças de 0 a 11 anos e idosos. Houve uma redução dos casos de feminicídio e mortes por intervenção policial. Os resultados evidenciaram que, com a pandemia, tem-se um efeito direto no número de homicídios. Considera-se os que este resultado tem relação direta com o distanciamento social, a elevação dos números de desempregados e a retração econômica das famílias.

Published
2022
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13. Controlling solid–liquid–solid GeSn nanowire growth modes by changing deposition sequences of a-Ge:H layer and SnO 2 nanoparticles

Author

Pere Roca i Cabarrocas, Edy Azrak, Wanghua Chen, Celia Castro, Ruiling Gong, Philippe Pareige, Sébastien Duguay, Ningbo University (NBU), Groupe de physique des matériaux (GPM), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), 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), Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), and Normandie Université (NU)

Subjects
Materials science, Annealing (metallurgy), Mechanical Engineering, Nanowire, Nanoparticle, Bioengineering, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Amorphous solid, [SPI.MAT]Engineering Sciences [physics]/Materials, Chemical engineering, Nanocrystal, Mechanics of Materials, Plasma-enhanced chemical vapor deposition, General Materials Science, Electrical and Electronic Engineering, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0210 nano-technology, Layer (electronics), Deposition (law), ComputingMilieux_MISCELLANEOUS
Abstract

Alloying Ge with Sn is one of the promising ways for achieving Si compatible optoelectronics. Here, GeSn nanowires (NWs) are realized via nano-crystallization of a hydrogenated amorphous Ge (a-Ge:H) layer with the help of metal Sn droplets. The full process consists of three steps: (1) SnO2 nanoparticle (NP) reduction in a hydrogen plasma to produce Sn catalyst; (2) a-Ge:H deposition at 120 °C and (3) annealing. GeSn alloys with rich morphologies such as discrete nanocrystals (NCs), random, and straight NWs were successfully synthesized by changing process conditions. We show that annealing under Ar plasma favors the elaboration of straight GeSn NWs in contrast to the conventional random GeSn NWs obtained when annealing is performed under a H2 atmosphere. Interestingly, GeSn in the form of discrete NCs can be fabricated during the deposition of a-Ge:H at 180 °C. Even more, the synthesis of out-of-plane GeSn NWs has been demonstrated by reversing the deposition sequence of SnO2 NPs and a-Ge:H layer.

Published
2021
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14. Controlling solid-liquid-solid GeSn nanowire growth modes by changing deposition sequences of a-Ge:H layer and SnO

Author

Ruiling, Gong, Edy, Azrak, Celia, Castro, Sébastien, Duguay, Philippe, Pareige, Pere, Roca I Cabarrocas, and Wanghua, Chen

Abstract

Alloying Ge with Sn is one of the promising ways for achieving Si compatible optoelectronics. Here, GeSn nanowires (NWs) are realized via nano-crystallization of a hydrogenated amorphous Ge (a-Ge:H) layer with the help of metal Sn droplets. The full process consists of three steps: (1) SnO

Published
2021

15. Correlation of luminescence measurements to the structural characterization of Pr3+-doped HfSiOx

Author

Etienne Talbot, Larysa Khomenkova, Rémi Demoulin, Celia Castro, Christophe Labbé, Fabrice Gourbilleau, Philippe Pareige, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), 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), V.E. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine (NASU), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), 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), 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
Photoluminescence, Materials science, Annealing (metallurgy), Cathodoluminescence, Biophysics, Analytical chemistry, 02 engineering and technology, Atom probe, 010402 general chemistry, 01 natural sciences, Biochemistry, law.invention, law, Rare-earth, Phase transition, Structural properties, General Chemistry, Sputter deposition, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Amorphous solid, Hafnium silicates, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Orthorhombic crystal system, 0210 nano-technology, Luminescence
Abstract

International audience; Luminescence and structural properties of Pr3+ doped HfSiOx thin layer elaborated by magnetron sputtering have been investigated as a function of the annealing temperature. The emission properties of Pr3+ ions were studied using photoluminescence (PL) and cathodoluminescence (CL) spectroscopies. Phase separation between amor- phous SiO2 and crystallized HfO2 nano-grains occurring in the HfSiOx matrix has been investigated by atom probe tomography and transmission electron microscopy with particular consideration for the Pr distribution. Both PL and CL measurements evidenced a strong emission originating from Pr3+ ions in the visible range for an annealing temperature higher than 950◦C. At 950◦C, Pr3+ ions are clearly located in HfO2 nano-grains of cubic structure. Regarding PL, no significant changes are observed between 950◦C and 1050◦C. However, CL mea- surements revealed new emission peaks in the infrared range after an annealing at 1050◦C, corresponding to the appearance of a new orthorhombic crystalline structure of HfO2 nano-grains in the thin layer. The CL signal evolution as a function of the annealing treatment is discussed in regard to the evolution of structural properties.

Published
2021
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16. Determinación de componentes nutricionales presentes en las hojas secas de Annona muricata L. (Guanábana)

Author

Jean Carlos Pérez Parra, Grabriela katerine Jaramillo García, Elizabeth Canchingre Bone, Osmir Cabrera Blanco, Celia Castro Rosero, and Maribel Cuello Pérez

Subjects
General Medicine
Abstract

La malnutrición sigue siendo un problema de salud para la humanidad. La búsqueda de alternativas para mejorarla es una de las metas de la organización mundial de la salud. Los productos elaborados a partir de plantas que aporten vitaminas, minerales y otros componentes, es interés de muchas instituciones e investigadores actualmente. Este trabajo está enmarcado en esta línea y tiene como Objetivo: Estudiar los componentes nutricionales presentes en la hoja seca de guanábana (Annona Muricata L.) y su posible aplicabilidad como suplemento nutricional. Métodos: Las hojas de guanábana se obtuvieron de plantas ubicadas en las provincias de Esmeraldas y Santo Domingo del Ecuador. Se realizó el secado a 60oC en un horno por 10 horas. A las muestras después de trituradas se les determinaron el contenido de humedad, cenizas, proteínas, fibras y extracto etéreo. También se cuantificaron minerales como: B, Ca, Cu, Fe, K, Mg, Mn, P y Zn y por último se analizó la cantidad de Vitamina C presente. Las determinaciones fueron realizadas por los métodos reportados en las normas INEN 2983-2015. Resultados: Este estudio demostró que hay variabilidad en los resultados de la caracterización de las hojas secas provenientes de Esmeraldas y Santo Domingo. El porcentaje de la humedad fue bajo, el de proteína estuvo entre 8,15 y 11,86%, el de extracto etéreo estuvo entre 6,77 y 8,48% y de fibra entre 23,90 y 24,30%. Se obtuvieron resultados positivos en todos los minerales estudiados, siendo mayores para el hierro y el calcio. Conclusión: Como conclusión tenemos que se caracterizó la hoja seca de guanábana y se cuenta con un producto que pudiera ser usado para la elaboración de un suplemento nutricional.

Published
2017
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17. Heavy Alkali Treatment of Cu(In,Ga)Se 2 Solar Cells: Surface versus Bulk Effects

Author

Roberto Félix, Sébastien Duguay, Enrico Avancini, Mohit Raghuwanshi, Martti J. Puska, Romain Carron, Milos Nesladek, Jakob Bombsch, Evelyn Handick, Nicoleta Nicoara, Celia Castro, Stephan Buecheler, Emilie Bourgeois, Ville Havu, Thomas Paul Weiss, Max Hilaire Wolter, Shigenori Ueda, Philip Jackson, Hannu-Pekka Komsa, Marcus Bär, Maria Malitckaya, Susanne Siebentritt, Giovanna Sozzi, Philippe Pareige, Dimitrios Hariskos, Arantxa Vilalta-Clemente, Thomas Kunze, Sascha Sadewasser, Roberto Menozzi, Florian Werner, Ayodhya N. Tiwari, Wolfram Witte, Regan G. Wilks, Université du Luxembourg (Uni.lu), Swiss Federal Laboratories for Materials Science and Technology [Dübendorf] (EMPA), Helmholtz Centre for Materials and Energy (HZB), Hasselt University (UHasselt), Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Zentrum fur Sonnenenergie-und Wasserstoff-Forschung (ZSW), Zentrum fur Sonnenenergie-und Wasserstoff-Forschung, Aalto University, University of Parma = Università degli studi di Parma [Parme, Italie], International Iberian Nanotechnology Laboratory (INL), National Institute for Materials Science (NIMS), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), 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), and Università degli studi di Parma = University of Parma (UNIPR)

Subjects
010302 applied physics, Surface (mathematics), Materials science, Renewable Energy, Sustainability and the Environment, chalcopyrite solar cells, Physics [G04] [Physical, chemical, mathematical & earth Sciences], grain boundaries, Large scale facilities for research with photons neutrons and ions, 02 engineering and technology, 021001 nanoscience & nanotechnology, Alkali metal, 01 natural sciences, recombination, Physique [G04] [Physique, chimie, mathématiques & sciences de la terre], Chemical engineering, alkali treatment, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], surface, General Materials Science, Grain boundary, bulk, 0210 nano-technology, Recombination, ComputingMilieux_MISCELLANEOUS
Abstract

Chalcopyrite solar cells achieve efficiencies above 23%. The latest improvements are due to post-deposition treatments (PDT) with heavy alkalis. This study provides a comprehensive description of the effect of PDT on the chemical and electronic structure of surface and bulk of Cu(In,Ga)Se-2. Chemical changes at the surface appear similar, independent of absorber or alkali. However, the effect on the surface electronic structure differs with absorber or type of treatment, although the improvement of the solar cell efficiency is the same. Thus, changes at the surface cannot be the only effect of the PDT treatment. The main effect of PDT with heavy alkalis concerns bulk recombination. The reduction in bulk recombination goes along with a reduced density of electronic tail states. Improvements in open-circuit voltage appear together with reduced band bending at grain boundaries. Heavy alkalis accumulate at grain boundaries and are not detected in the grains. This behavior is understood by the energetics of the formation of single-phase Cu-alkali compounds. Thus, the efficiency improvement with heavy alkali PDT can be attributed to reduced band bending at grain boundaries, which reduces tail states and nonradiative recombination and is caused by accumulation of heavy alkalis at grain boundaries. This work was supported by the European Union's Horizon 2020 research and innovation program under grant agreement no. 641004 (Sharc25) and by the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number 15.0158. Siebentritt, S (reprint author), Univ Luxembourg, Lab Photovolta, Phys & Mat Sci Res Unit, 41 Rue Brill, L-4422 Belvaux, Luxembourg. susanne.siebentritt@uni.lu

Published
2020
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18. Evidence of Mg segregation to threading dislocation in normally-off GaN-HEMT

Author

Sébastien Duguay, Andres Echeverri, Celia Castro, Olivier Latry, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, business.industry, Doping, Normally off, 02 engineering and technology, Substrate (electronics), High-electron-mobility transistor, Atom probe, 021001 nanoscience & nanotechnology, Computer Science Applications, law.invention, [SPI.MAT]Engineering Sciences [physics]/Materials, law, Threading (manufacturing), Optoelectronics, Electrical and Electronic Engineering, Diffusion (business), Dislocation, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0210 nano-technology, business, ComputingMilieux_MISCELLANEOUS
Abstract

In this article, the segregation of Mg to threading dislocation is demonstrated in a commercial normally-off GaN High Electron Mobility Transistor using atom probe tomography. The diffusion of Mg from a doped p-type GaN gate through the AlGaN buffer to the GaN substrate is demonstrated.

Published
2019
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19. Influence of RbF post deposition treatment on heterojunction and grain boundaries in high efficient (21.1%) Cu(In,Ga)Se2 solar cells

Author

Mohit Raghuwanshi, Celia Castro, Philippe Pareige, Dimitrios Hariskos, Wolfram Witte, Arantxa Vilalta-Clemente, Emmanuel Cadel, Philip L. Jackson, Sébastien Duguay, Groupe de physique des matériaux (GPM), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), 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), Rheinisch-Westfälische Technische Hochschule Aachen University (RWTH), Zentrum fur Sonnenenergie-und Wasserstoff-Forschung (ZSW), Zentrum fur Sonnenenergie-und Wasserstoff-Forschung, Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), and RWTH Aachen University

Subjects
Materials science, Analytical chemistry, 02 engineering and technology, Atom probe, 010402 general chemistry, 01 natural sciences, law.invention, [SPI.MAT]Engineering Sciences [physics]/Materials, chemistry.chemical_compound, law, General Materials Science, Electrical and Electronic Engineering, Rubidium fluoride, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, ComputingMilieux_MISCELLANEOUS, Renewable Energy, Sustainability and the Environment, Chalcopyrite, Heterojunction, 021001 nanoscience & nanotechnology, Copper indium gallium selenide solar cells, 0104 chemical sciences, chemistry, Transmission electron microscopy, visual_art, visual_art.visual_art_medium, Grain boundary, 0210 nano-technology, Deposition (chemistry)
Abstract

Post deposition treatments (PDT) by alkali fluorides applied to chalcopyrite-based absorbers have produced record efficiencies in thin-film solar devices in the past few years and recently the efficiency of 22.6% was achieved with Cu(In,Ga)Se2 (CIGS) using rubidium fluoride (RbF) PDT. However, the effects of RbF-PDT towards changes in its interfacial and grain boundary (GB) properties are still not fully understood. In this work, cells with efficiency higher than 21% are investigated by combination of atom probe tomography (APT) and transmission electron microscopy (TEM) to show how changes in GB and interface chemistry may facilitate high efficiencies. APT studies, carried out at the interface between CIGS absorber and solution-grown CdS buffer layer, show In enrichment and Cu depletion along with traces of Rb. Our APT studies reveal higher amounts of Rb (1.5 at. %) and lower amounts of Na and K (

Published
2019
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20. Layered tellurides: stacking faults induce low thermal conductivity in the new In2Ge2Te6 and thermoelectric properties of related compounds

Author

David Berthebaud, Robin Lefèvre, Stéphanie Gascoin, Franck Gascoin, Oleg I. Lebedev, Celia Castro, Daniel Chateigner, Olivier Perez, Laboratoire de cristallographie et sciences des matériaux (CRISMAT), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Université de Rouen Normandie (UNIROUEN), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-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)-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 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes-Centre National de la Recherche Scientifique (CNRS), Laboratoire des matériaux et du génie physique (LMGP), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), and Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Renewable Energy, Sustainability and the Environment, Analytical chemistry, Mineralogy, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Thermoelectric materials, 01 natural sciences, 0104 chemical sciences, Thermal conductivity, Electrical resistivity and conductivity, Seebeck coefficient, Thermoelectric effect, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, Crystallite, 0210 nano-technology, Ternary operation, Single crystal
Abstract

International audience; A new ternary layered compound In2Ge2Te6, belonging to the hexatellurogermanate family has been synthesized from the reaction of appropriate amounts of the pure elements at high temperature in sealed silica tubes. In2Ge2Te6 crystallizes in the rhombohedral space-group R[3 with combining macron]:H with lattice parameters a = 7.0863(3) Å and c = 21.206(2) Å and its structure is resolved using single crystal X-ray diffraction. The transport properties (Seebeck coefficient, resistivity and thermal conductivity) of compounds belonging to the family AMTe3 (A = In and Cr; M = Ge and Si) are reported. All compounds are p-type semiconductors. InSiTe3 and Cr2Si2Te6 are too resistive to be good thermoelectric materials, with maximal power factors of 10−6 and 10−5 W m−2 K−2 at 473 K, while In2Ge2Te6 and Cr2Ge2Te6 exhibit maximal values of about 10−4 and 10−3 W m−2 K−2 at 673 K, respectively. All compounds exhibit thermal conductivity below 2 W m−1 K−1, with values dropping to 0.35 W m−1 K−1 at 673 K for In2Ge2Te6. Transmission electron microscopy evidences stacking faults explaining such low thermal conductivities. The best ZT values are observed for Cr2Ge2Te6 with 0.45 at 773 K and In2Ge2Te6 with 0.18 at 673 K. Among these layered structures, a spark plasma sintered Cr2Ge2Te6 sample exhibits some thermal conductivity anisotropy but only weakly due to crystallite orientations.

Published
2017
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21. Reverse Monte Carlo reconstruction algorithm for discrete electron tomography based on HAADF-STEM atom counting

Author

F. Moyon, Celia Castro, M. D. Robertson, Williams Lefebvre, A. Etienne, and D. Hernández-Maldonado

Subjects
010302 applied physics, Physics, Histology, Monte Carlo method, Reconstruction algorithm, 02 engineering and technology, Reverse Monte Carlo, 021001 nanoscience & nanotechnology, 01 natural sciences, Pathology and Forensic Medicine, Computational physics, law.invention, Electron tomography, Transmission (telecommunications), law, 0103 physical sciences, Atom, Particle, Atomic physics, Electron microscope, 0210 nano-technology
Abstract

Summary In this paper, we propose an algorithm to obtain a three-dimensional reconstruction of a single nanoparticle based on the method of atom counting. The location of atoms in three dimensions has been successfully performed using simulations of high-angle-annular-dark-field images from only three zone-axis projections, [110], [310] and [211], for a face-centred cubic particle. These three orientations are typically accessible by low-tilt holders often used in high-performance scanning transmission electron microscopes.

Published
2016
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22. Origin of Pr 3+ luminescence in hafnium silicate films: combined atom probe tomography and TEM investigations

Author

Georges Beainy, Celia Castro, Christophe Labbé, Fabrice Gourbilleau, Larysa Khomenkova, Rémi Demoulin, Philippe Pareige, Etienne Talbot, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), 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), 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)-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)-Université de Caen Normandie (UNICAEN), 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), 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, phase transformation, Biomedical Engineering, chemistry.chemical_element, Bioengineering, 02 engineering and technology, Atom probe, 010402 general chemistry, 01 natural sciences, law.invention, [SPI.MAT]Engineering Sciences [physics]/Materials, [PHYS.PHYS.PHYS-COMP-PH]Physics [physics]/Physics [physics]/Computational Physics [physics.comp-ph], chemistry.chemical_compound, law, General Materials Science, Electrical and Electronic Engineering, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, hafnium silicates, rare-earth ions, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, Silicate, 0104 chemical sciences, Hafnium, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, chemistry, atom probe tomography, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Physical chemistry, photoluminescence, 0210 nano-technology, Luminescence
Abstract

International audience; Origin of Pr 3+ luminescence in hafnium silicate films: combined atom probe tomography and TEM investigations To cite this article: Rémi Demoulin et al 2018 Nano Futures 2 035005 View the article online for updates and enhancements. Related content Thermal stability of high-k Si-rich HfO2 layers grown by RF magnetron sputtering L Khomenkova, X Portier, J Cardin et al.-High-k Hf-based layers grown by RF magnetron sputtering L Khomenkova, C Dufour, P-E Coulon et al.-XRD and EXAFS studies on the structure of Er3+-doped SiO2–HfO2 glass-ceramic waveguides: Er3+-activated HfO2 Abstract Structural, chemical, and luminescence properties of Pr 3+-doped HfSiO x layers fabricated by radio-frequency magnetron sputtering were examined as a function of annealing temperature. Phase separation between SiO 2 and HfO 2 as well as the location of Pr 3+ dopants were investigated using atom probe tomography and transmission electron microscopy while optical properties of Pr 3+ ions were studied using photoluminescence measurements. As a result, (i) we evidenced the location of the Pr 3+ dopants in the HfO 2 phase while the SiO 2 phase was discovered to be free of these dopants, (ii) the HfO 2 phase was identified to crystallize in the cubic phase until 1050 °C annealing, (iii) no Pr clusters were detected as function of annealing, and (iv) luminescence properties were discussed in regard to the location of Pr in the HfO 2 cubic phase.

Published
2018
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23. Rubidium distribution at atomic scale in high efficient Cu(In,Ga)Se2 thin-fil solar cells

Author

Arantxa Vilalta-Clemente, Mohit Raghuwanshi, Sébastien Duguay, Celia Castro, Emmanuel Cadel, Philippe Pareige, Philip Jackson, Roland Wuerz, Dimitrios Hariskos, and Wolfram Witte

Subjects
CIGS, thin-film solar cells, high efficiency, alkali elements
Abstract

The introduction of a rubidium fluoride post deposition treatment (RbF-PDT) for Cu(In,Ga)Se2 (CIGS) absorber layers has led to a record efficiency up to 22.6% for thin-film solar cell technology. In the present work, high efficiency CIGS samples with RbF-PDT have been investigated by atom probe tomography (APT) to reveal the atomic distribution of all alkali elements present in CIGS layers and compared with non-treated samples. A Scanning Electron Microscopy Dual beam station (Focused Ion Beam–Gas Injection System) as well as Transmission Kikuchi diffraction is used for atom probe sample preparation and localization of the grain boundaries (GBs) in the area of interest. The analysis of the 3D atomic scale APT reconstructions of CIGS samples with RbF-PDT shows that inside grains, Rb is under the detection limit, but the Na concentration is enhanced as compared to the reference sample without Rb. At the GBs, a high concentration of Rb reaching 1.5 at. % was found, and Na and K (diffusing from the glass substrate) are also segregated at GBs but at lower concentrations as compared to Rb. The intentional introduction of Rb leads to significant changes in the chemical composition of CIGS matrix and at GBs, which might contribute to improve device efficiency.

Published
2018

24. First transparent oxide ion conducting ceramics synthesized by full crystallization from glass

Author

Celia Castro, Cécile Genevois, Ling Bing Kong, Alberto José Fernández Carrión, Dominique Thiaudière, Guy Matzen, Marina Boyer, Denis Pelloquin, Xiaoyan Yang, Emmanuelle Suard, Emmanuel Véron, Mathieu Allix, Louis Hennet, Quanchao Wang, Xiaojun Kuang, Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Guilin University of Electronic Technology, Institut Laue-Langevin (ILL), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Groupe de physique des matériaux (GPM), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), 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), Laboratoire de cristallographie et sciences des matériaux (CRISMAT), Normandie Université (NU)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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), Nanyang Technological University [Singapour], College of materials science and engineering, Guilin University of Technology, ILL, Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Institut de Chimie du CNRS (INC), and Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université d'Orléans (UO)

Subjects
Materials science, Oxide, 02 engineering and technology, Conductivity, engineering.material, 010402 general chemistry, 01 natural sciences, law.invention, chemistry.chemical_compound, law, Phase (matter), General Materials Science, Ceramic, Crystallization, ComputingMilieux_MISCELLANEOUS, Birefringence, Renewable Energy, Sustainability and the Environment, Melilite, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Chemical engineering, chemistry, visual_art, visual_art.visual_art_medium, engineering, Grain boundary, 0210 nano-technology
Abstract

International audience; We propose here to use full crystallization from glass as an innovative process to elaborate completely dense transparent oxide conductors. This is demonstrated in the case of new non-stoichiometric Ln1+xSr1−xGa3O7+δ (Ln = Eu, Gd or Tb) melilite ceramics which show bulk conductivity greater than 0.02 S cm−1 at 500 °C. Full crystallization from glass is used here as an alternative method to conventional solid state synthesis in order to elaborate new crystalline phases, i.e. melilite compositions with small rare earth elements, which could not be synthesized by a solid state reaction. The materials are stable up to 800 °C under cycled conductivity measurement conditions. Moreover, as melilite compositions show similar glass and crystalline phase densities, the process can produce fully dense ceramics with thin grain boundaries. Coupled to the limited birefringence of the melilite structure, such materials retain some of the glass transparency during crystallization, leading to the first transparent oxide ion conducting ceramics. This work may open a way to a new class of fully dense, and possibly transparent, solid state electrolytes.

Published
2018
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25. Fabrication of well-ordered arrays of silicon nanocrystals using a block copolymer mask

Author

Celia Castro, Gabriele Seguini, M. Perego, Paolo Pellegrino, Sylvie Schamm-Chardon, Gerard Ben Assayag, A Andreozzi, and Federico Ferrarese Lupi

Subjects
010302 applied physics, Materials science, Fabrication, Ion beam, business.industry, Nanoparticle, Nanotechnology, 02 engineering and technology, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Nanocrystal, 0103 physical sciences, Materials Chemistry, Deposition (phase transition), Self-assembly, Electrical and Electronic Engineering, Photonics, 0210 nano-technology, business, Nanoscopic scale
Abstract

The block copolymer self-assembly provides a reliable tool for the planar organization of materials at the nanoscale. In this paper, we review our recent achievements in the case of the polystyrene-b-poly(methyl-methacrylate) (PS-b-PMMA) polymeric mixture. By the proper choice of deposition and treatment parameters, one can adjust the thickness of the deposited material and transfer the block copolymer cylindrical organization to the material inclusions into the matrix. Silicon nanocrystals (Si-ncs) have been used as the active material to process, due to its interesting electrical and optical properties for electronic and photonic applications. This material has been fabricated in the form of well-defined arrays over a macroscopic surface, either by electron beam deposition or by ion beam synthesis. A further, crucial step toward the fabrication of the active area of the device is the formation of Si nanoparticle arrays onto sub-micrometric trenches defined by graphoepitaxy. The periodicity and the topography of the trenches highly affect the possibility of a conformal deposition of the ordered block polymeric mask, and consequently, of the reproduction of the patterned array of nanocrystals.

Published
2013
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26. Nanoscale control of Si nanoparticles within a 2D hexagonal array embedded in SiO2 thin films

Author

Gérard Benassayag, Michele Perego, A Andreozzi, Sylvie Schamm-Chardon, Béatrice Pécassou, Gabriele Seguini, Celia Castro, Matériaux et dispositifs pour l'Electronique et le Magnétisme (CEMES-MEM), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratorio MDM (IMM-CNR), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), NanoSci-E+ - ANR-08-NSCI-003: NANOBLOCK, ANR-08-NSCI-0003,NANO-BLOCK(2008), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), and Consiglio Nazionale delle Ricerche [Roma] (CNR)

Subjects
010302 applied physics, [PHYS]Physics [physics], Fabrication, Materials science, Ion beam, Nanoporous, Mechanical Engineering, Nanoparticle, Bioengineering, Nanotechnology, 02 engineering and technology, General Chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Mechanics of Materials, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Energy filtered transmission electron microscopy, General Materials Science, Electrical and Electronic Engineering, Thin film, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 0210 nano-technology, Lithography, Nanoscopic scale
Abstract

International audience; In this work, we investigate the ability to control Si nanoparticles (NPs) spatially arranged in a hexagonal network of 20 nm wide nanovolumes at controlled depth within SiO2 thin films. To achieve this goal an unconventional lithographic technique was implemented based on a bottom-up approach, that is fully compatible with the existing semiconductor technology. The method combines ultra-low energy ion beam synthesis with nanostructured block-copolymer thin films that are self-assembled on the SiO2 substrates to form a nanoporous template with hexagonally packed pores. A systematic analytical investigation using time of flight-secondary ion mass spectroscopy and low-loss energy filtered transmission electron microscopy demonstrates that by adjusting few fabrication parameters, it is possible to narrow the size distribution of the NPs and to control the number of NPs per nanovolume. Experimental results are critically discussed on the basis of literature data, providing a description of the mechanism involved in the formation of Si NPs.

Published
2017
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27. Combining TEM and APT for a better understanding of super high efficiency Cu(In,Ga)Se2 thin film solar cells

Author

Friedrich Kessler, Romain Carron, Sébastien Duguay, Philippe Pareige, Emmanuel Cadel, Enrico Avancini, Mohit Raghuwanshi, Wolfram Witte, Stephan Buecheler, Celia Castro, Dimitrios Hariskos, Ayodhya N. Tiwari, Benjamin Bissig, Philip L. Jackson, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Zentrum fur Sonnenenergie-und Wasserstoff-Forschung, Swiss Federal Laboratories for Materials Science and Technology [Dübendorf] (EMPA), European Microscopy Society, 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, business.industry, Photovoltaic system, Optoelectronics, Thin film solar cell, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], business, 7. Clean energy, Copper indium gallium selenide solar cells, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016
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28. Nanoscale control of Si nanoparticles within a 2D hexagonal array embedded in SiO

Author

Celia, Castro, Gérard, BenAssayag, Béatrice, Pecassou, Andrea, Andreozzi, Gabriele, Seguini, Michele, Perego, and Sylvie, Schamm-Chardon

Abstract

In this work, we investigate the ability to control Si nanoparticles (NPs) spatially arranged in a hexagonal network of 20 nm wide nanovolumes at controlled depth within SiO

Published
2016

29. Correlative Investigations by HAADF-STEM and Atom Probe Tomography

Author

Williams Lefebvre, Florian Moyon, Antoine Normand, Nicolas Rolland, Ivan Blum, Auriane Etienne, Celia Castro, Fabien Cuvilly, Lorenzo Mancini, Isabelle Mouton, Lorenzo Rigutti, François Vurpillot, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2016
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30. Nature of the Catalyst Particles in CCVD Synthesis of Multiwalled Carbon Nanotubes Revealed by the Cooling Step Study

Author

Mathieu Pinault, Pascale Launois, Celia Castro, Julien Cambedouzou, Vasile Heresanu, Odile Stéphan, Cécile Reynaud, Martine Mayne-L’Hermite, Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Quenching, Materials science, Electron energy loss spectroscopy, Nanotechnology, 02 engineering and technology, Carbon nanotube, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Catalysis, law.invention, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Condensed Matter::Materials Science, Chemical state, General Energy, Electron diffraction, Chemical engineering, law, Carbon nanotube supported catalyst, Physical and Theoretical Chemistry, 0210 nano-technology, Pyrolysis
Abstract

The true chemical nature and physical state of the catalyst particles in Catalytic Chemical Vapor Deposition (CCVD) synthesis of carbon nanotubes are the subject of intense discussions, as it is one of the keys to understand their growth mechanisms. The CCVD method considered in this article involves pyrolysis of mixed liquid aerosols and leads to the synthesis of large carpets of multiwalled nanotubes (MWNTs) partially filled with iron-based materials. The experimental approach consists in studying the influence of the cooling procedure applied at the end of the synthesis. Both slow standard cooling or quenching were performed, and the structure and chemical state of the iron-based particles were compared through complementary local and global investigations involving X-ray diffraction, electron microscopy, electron diffraction, as well as electron energy loss spectroscopy. We clearly demonstrate that iron-based catalyst particles are carbon-rich and oxygen-free in quenched samples, and that they oxidize during the slow cooling step. It is inferred that they are very probably molten supersaturated carbon-metal particles during the NT growth.

Published
2008
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31. Evolution of shape, size, and areal density of a single plane of Si nanocrystals embedded in SiO2 matrix studied by atom probe tomography

Author

Bin Han, Gerard Ben Assayag, Celia Castro, Michele Perego, Yasuyoshi Nagai, Yasuo Shimizu, Koji Inoue, Gabriele Seguini, Elisa Arduca, Sylvie Schamm-Chardon, WPI Advanced Institute for Materials Research (WPI-AIMR), Tohoku University [Sendai], Laboratorio MDM (IMM-CNR), Consiglio Nazionale delle Ricerche [Roma] (CNR), Matériaux et dispositifs pour l'Electronique et le Magnétisme (CEMES-MEM), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Silicon, Materials science, E beam evaporation, Annealing (metallurgy), General Chemical Engineering, Layer thickness, Analytical chemistry, chemistry.chemical_element, High resolution transmission electron microscopy, 02 engineering and technology, Atom probe, Multilayer structures, 01 natural sciences, law.invention, Areal densities, law, 0103 physical sciences, Energy filtered transmission electron microscopy, Area density, High-resolution transmission electron microscopy, 010302 applied physics, [PHYS]Physics [physics], Si nanocrystal, General Chemistry, 021001 nanoscience & nanotechnology, Nanocrystals, Atom probe tomography, chemistry, Nanocrystal, Transmission electron microscopy, Probes, Si (100) substrate, 0210 nano-technology
Abstract

cited By 4; International audience; Single planes of Si nanocrystals (NCs) embedded in a SiO2 matrix were synthesized by annealing SiO2/SiO/SiO2 multilayer structures deposited on Si (100) substrates by e-beam evaporation. The dependence of the shape, size, and areal density of Si NCs on the thickness of the initial SiO layer was investigated using atom probe tomography and validated by energy filtered transmission electron microscopy. Three kinds of samples were prepared with SiO layer thicknesses of 4, 6, and 10 nm. The size of Si NCs enlarged with increasing SiO layer thickness. The shape of Si NCs was mainly extended spheroid in all three kinds of samples. In the sample with the 4 nm-thick SiO layer, the Si NCs were more prolate than those in the other two samples. Moreover, many rod-shaped Si NCs appeared in the sample with the 10 nm-thick SiO layer. These rod-shaped Si NCs were found to be connected by small Si NCs. The areal densities of Si NCs were in the order of 1012 NCs per cm2 in all samples. © 2016 The Royal Society of Chemistry.

Published
2016
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32. Structural and optical study of Ce segregation in Ce-doped SiO 1.5 thin films

Author

Hervé Rinnert, Jennifer Weimmerskirch-Aubatin, Etienne Talbot, Michel Vergnat, Georges Beainy, Celia Castro, Philippe Pareige, Mathieu Stoffel, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Institut Jean Lamour (IJL), Institut de Chimie du CNRS (INC)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), 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, Photoluminescence, Materials science, Silicon, Annealing (metallurgy), Inorganic chemistry, Doping, Analytical chemistry, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, Atom probe, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, Cerium, chemistry, law, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Thin film, 0210 nano-technology, Luminescence
Abstract

International audience; Cerium doped SiO 1.5 thin films fabricated by evaporation and containing silicon nanocrystals were investigated by atom probe tomography. The effect of post-growth annealing treatment has been systematically studied to correlate the structural properties obtained by atom probe tomography to the optical properties measured by photoluminescence spectroscopy. The atom probe results demonstrated the formation of Ce-Si rich clusters upon annealing at 900 C which leads to a drastic decrease of the Ce-related luminescence. At 1100 C, pure Si nanocrystals and optically active cerium silicate compounds are formed. Consequently, the Ce-related luminescence is found to reappear at this temperature while no Si-nanocrystal related luminescence is observed for films containing more than 3% Ce. V C 2015 AIP Publishing LLC. [http://dx.

Published
2015
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33. Effect of doping on the morphology of GaSb/GaAs nanostructures for solar cells

Author

Celia Castro, N. Fernández-Delgado, Sergio I. Molina, Anthony Krier, Juanita James, Stephanie Duguay, Miriam Herrera, University of Cadiz, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Lancaster University, 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Morphology (linguistics), Nanostructure, Materials science, Dopant, business.industry, Doping, General Physics and Astronomy, Nanotechnology, Heterojunction, Surfaces and Interfaces, General Chemistry, Crystal structure, Condensed Matter Physics, Epitaxy, Surfaces, Coatings and Films, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, Thin film, business, ComputingMilieux_MISCELLANEOUS
Abstract

The effect of the introduction of dopants on the morphology of GaSb/GaAs nanostructures is analyzed by HAADF-STEM.1 Our results show the presence of well-developed GaSb QRs2 in both p-doped and n-doped heterostructures. However, in the undoped sample grown under the same conditions such well-developed QRs have not been observed. We found that p-doping with Be stimulates the formation of QRs, whereas n-doping with Te results in the formation of GaSb nanocups. Therefore, the introduction of dopants in the growth of GaSb nanostructures has a significant effect on their morphology.

Published
2015
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34. Atomic characterization of Au clusters in vapor-liquid-solid grown silicon nanowires

Author

Didier Stiévenard, Bruno Grandidier, Wanghua Chen, Celia Castro, Tao Xu, Philippe Pareige, Pere Roca i Cabarrocas, Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), University of Connecticut (UCONN), 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), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Microscope, Scanning electron microscope, Nanowire, Analytical chemistry, General Physics and Astronomy, 02 engineering and technology, Atom probe, 01 natural sciences, Focused ion beam, law.invention, Condensed Matter::Materials Science, law, 0103 physical sciences, Scanning transmission electron microscopy, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS, 010302 applied physics, business.industry, 021001 nanoscience & nanotechnology, Transmission electron microscopy, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, Scanning tunneling microscope, 0210 nano-technology, business
Abstract

By correlating atom probe tomography with other conventional microscope techniques (scanning electron microscope, scanning transmission electron microscope, and scanning tunneling microscopy), the distribution and composition of Au clusters in individual vapor-liquid-solid grown Si nanowires is investigated. Taking advantage of the characteristics of atom probe tomography, we have developed a sample preparation method by inclining the sample at certain angle to characterize the nanowire sidewall without using focused ion beam. With three-dimensional atomic scale reconstruction, we provide direct evidence of Au clusters tending to remain on the nanowire sidewall rather than being incorporated into the Si nanowires. Based on the composition measurement of Au clusters (28% ± 1%), we have demonstrated the supersaturation of Si atoms in Au clusters, which supports the hypothesis that Au clusters are formed simultaneously during nanowire growth rather than during the cooling process.

Published
2015
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35. Knowledge Governance : Reasserting the Public Interest

Author

Leonardo Burlamaqui, Anna Célia Castro, Rainer Kattel, Leonardo Burlamaqui, Anna Célia Castro, and Rainer Kattel

Subjects
Knowledge management
Abstract

This book argues that the current international intellectual property rights regime, led by the World Trade Organization (WTO), has evolved over the past three decades toward overemphasizing private interests and seriously hampering public interests in access to knowledge and innovation diffusion. While it is obvious that firm-level dynamics are changing – toward networks and peer production in technologically leading companies in the developed countries, and toward increasing integration into global and regional production and innovation networks in developing countries – academic discussions as well as policy disputes in the WTO and other international forums take place within a rather rigid and narrow perspective. This approach concentrates on tangible and codified knowledge creation and diffusion in research and development (R&D) that can be protected via patents and other intellectual property rules and regulations. In terms of global policy initiatives, however, it is becoming increasingly clear that the WTO in particular is mostly a conflict-resolution facility rather than a global governance body able to generate cooperation and steer international coordinated policy action. At the same time, rent extraction and profits streaming from legal hyperprotection have become pervasively important for firm strategies to compete in a globalized marketplace. Taking into account these structural changes, the new frontiers that have to be faced by industrial, technological, innovation and competition policies, as well as increasingly complex coordination problems rising among them, a major cluster of policy and institutional design challenges emerges. To address them, a new conceptual framework is necessary. This volume proposes “knowledge governance” as the adequate framework to meet this challenge. Knowledge governance is an analytical framework that embraces different forms of public governance mechanisms such as supervision, rulemaking, regulation, policy prescriptions and institutional coordination and applies them to the realms of knowledge production, diffusion and appropriation.

Published
2012

36. Silicon crystallization in nanodot arrays organized by block copolymer lithography

Author

Celia Castro, Gabriele Seguini, Michele Perego, A Andreozzi, Sylvie Schamm-Chardon, Gérard Benassayag, Laboratorio MDM (IMM-CNR), Consiglio Nazionale delle Ricerche [Roma] (CNR), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Matériaux et dispositifs pour l'Electronique et le Magnétisme (CEMES-MEM), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), NanoSci-E+ - ANR-08-NSCI-003: NANOBLOCK, ANR-08-NSCI-0003,NANO-BLOCK(2008), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)

Subjects
Amorphous silicon, electron beam, Nanoporous templates, synthesis, crystallization, Silicon oxides, law.invention, evaporation, high temperature, chemistry.chemical_compound, law, Electron beam evaporation, General Materials Science, Crystallization, [PHYS]Physics [physics], density, Nanoporous, Lateral distributions, Block copolymer lithography, quantum dot, Self-assembly, Nanostructured materials, Self assembly, Condensed Matter Physics, Block copolymers, Atomic and Molecular Physics, and Optics, Nanocrystals, unclassified drug, Si nanocrystals, silicon nanodot, Transmission electron microscopy, Modeling and Simulation, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Nanodot, Specific substrates, High-temperature annealing, Materials science, E beam evaporation, Silicon, Nanolithography, chemistry.chemical_element, Bioengineering, Nanotechnology, film, Electron beam physical vapor deposition, Article, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Si nanocrystal, copolymer, silicon, General Chemistry, Amorphous solid, chemistry, Chemical engineering, TEM, polystyrene b polymethylmethacrylate block copolymer, E-beam evaporation, Amorphous films
Abstract

cited By 2; International audience; Asymmetric polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers are used to fabricate nanoporous PS templates with different pore diameter depending on the specific substrate neutralization protocol. The resulting polymeric templates are used as masks for the subsequent deposition of a thin (h = 5 nm) amorphous Si layer by electron beam evaporation. After removal of the polymeric film and of the silicon excess, well-defined hexagonally packed amorphous Si nanodots are formed on the substrate. Their average diameter (d

Published
2014
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37. Scaling size of the interplay between quantum confinement and surface related effects in nanostructured silicon

Author

Celia Castro, Sylvie Schamm-Chardon, Gabriele Seguini, Michele Perego, Gérard Benassayag, Paolo Pellegrino, Laboratorio MDM (IMM-CNR), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Matériaux et dispositifs pour l'Electronique et le Magnétisme (CEMES-MEM), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Universitat de Barcelona (UB), NanoSci-E+ - ANR-08-NSCI-003: NANOBLOCK, ANR-08-NSCI-0003,NANO-BLOCK(2008), Consiglio Nazionale delle Ricerche [Roma] (CNR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)

Subjects
[PHYS]Physics [physics], Materials science, Physics and Astronomy (miscellaneous), Silicon, Condensed matter physics, Band gap, chemistry.chemical_element, Nanotechnology, 02 engineering and technology, 021001 nanoscience & nanotechnology, Thermal conduction, 01 natural sciences, chemistry, Quantum dot, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 010306 general physics, 0210 nano-technology, Electronic band structure, Quantum, Scaling, Surface states
Abstract

International audience; Si nanocrystals (NCs) embedded in a SiO2 matrix provide an exemplar curved nanostructured interface to evidence the competition between surface states and quantum confinement (QC) effects. The study of the energy band alignment as a function of NCs size (

Published
2013
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38. The role of hydrogen in the aerosol-assisted chemical vapor deposition process in producing thin and densely packed vertically aligned carbon nanotubes

Author

Celia Castro, Mathieu Pinault, Martine Mayne-L’Hermite, Dominique Porterat, Cécile Reynaud, Laboratoire Francis PERRIN (LFP - URA 2453), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Hydrogen, Nucleation, Nanoparticle, chemistry.chemical_element, Nanotechnology, 02 engineering and technology, Chemical vapor deposition, Carbon nanotube, 010402 general chemistry, 7. Clean energy, 01 natural sciences, law.invention, Catalysis, chemistry.chemical_compound, law, General Materials Science, Thermal decomposition, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Ferrocene, chemistry, Chemical engineering, 0210 nano-technology
Abstract

International audience; Aerosol-assisted catalytic chemical vapor deposition (CCVD) is an efficient single-step process to synthesize vertically aligned carbon nanotube (VACNT) arrays from ferrocene and toluene precursors. While no promoters are needed, adding hydrogen to the carrier gas assists the process. In order to understand the role of hydrogen, we performed syntheses at 850 and 800 °C. The product distribution along the length of the reactor was analyzed by electron microscopy to follow the effect of the hydrogen, as well as the characteristics of the CNT and catalyst nanoparticles. Increasing the hydrogen content shifts the CNT growth towards the furnace entrance and strongly reduces the CNT diameters, while the CNT number density increases. Hydrogen demonstrably affects the gas phase phenomena by lowering the decomposition temperature of ferrocene and increasing the nucleation site density of the catalytic nanoparticles. The yield under hydrogen remains reasonable in the aerosol-assisted CCVD process, and is even improved at 800 °C. Hydrogen content appears to be an interesting parameter to control the characteristics of vertically aligned CNT.

Published
2013
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39. In-plane organization of silicon nanocrystals embedded in SiO2 thin films

Author

Gérard Benassayag, Béatrice Pécassou, Gabriele Seguini, Sylvie Schamm-Chardon, Celia Castro, A Andreozzi, Michele Perego, Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratorio MDM (IMM-CNR), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), NanoSci-E+ - ANR-08-NSCI-003: NANOBLOCK, ANR-08-NSCI-0003,NANO-BLOCK(2008), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), and Consiglio Nazionale delle Ricerche [Roma] (CNR)

Subjects
Materials science, Nanostructure, Ion beam, Bioengineering, Nanotechnology, 02 engineering and technology, 01 natural sciences, 0103 physical sciences, Microelectronics, General Materials Science, Electrical and Electronic Engineering, Thin film, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, Nanoscopic scale, 010302 applied physics, [PHYS]Physics [physics], business.industry, Nanoporous, Mechanical Engineering, General Chemistry, 021001 nanoscience & nanotechnology, Nanolithography, Nanocrystal, Mechanics of Materials, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, business
Abstract

International audience; Nanofabrication of buried structures with dimensions below 5 nm and with controlled 3D-positioning at the nanoscale was attempted to open new routes to future nanodevices where single nanostructures could be systematically interfaced. A typical example is ultralow-energy ion beam synthesis where already the depth positioning of embedded arrays of silicon nanocrystals can be finely controlled with nanometric precision. In this study, we investigated for the first time the control of the in-plane organization of the nanocrystals using a legitimate patterning option for microelectronic industries, self-assembled block-copolymer. The compatibility with the ultralow-energy ion beam synthesis process of polymeric nanoporous films used as mask was demonstrated together with the capability to control in 3D the organization of Si nanocrystals. The resulting nano-organization consists in a hexagonal array of 20 nm wide nanovolumes containing on average 8 nanocrystals embedded at a controlled depth within a silica matrix.

Published
2013
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40. Extraction of the characteristics of Si nanocrystals by the charge pumping technique

Author

Regis Diaz, Sylvie Schamm-Chardon, Panagiotis Dimitrakis, Gérard Benassayag, Béatrice Pécassou, Celia Castro, Jérémie Grisolia, Pascal Normand, Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA), National Center for Scientific Research 'Demokritos' (NCSR), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), and Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)

Subjects
Silicon, Materials science, Static Electricity, Analytical chemistry, Physics::Optics, chemistry.chemical_element, Bioengineering, 02 engineering and technology, Dielectric, 01 natural sciences, Condensed Matter::Materials Science, Tunnel effect, Microscopy, Electron, Transmission, 0103 physical sciences, Microscopy, Materials Testing, Energy filtered transmission electron microscopy, General Materials Science, Electrical and Electronic Engineering, Particle Size, Quantum tunnelling, [PHYS]Physics [physics], 010302 applied physics, business.industry, Mechanical Engineering, General Chemistry, Equipment Design, 021001 nanoscience & nanotechnology, Semimetal, Nanostructures, Equipment Failure Analysis, chemistry, Mechanics of Materials, Transmission electron microscopy, Optoelectronics, 0210 nano-technology, business
Abstract

International audience; In this paper, the characteristics of silicon nanocrystals used as charge trapping centers in memory devices are examined using the two-level charge pumping (CP) technique performed as a function of frequency and energy filtered transmission electron microscopy (EFTEM). The parameters extracted from the two methods such as the depth location, density and effective diameter of the nanocrystals are in good quantitative agreement. These results validate the charge pumping approach as a non-destructive powerful technique to access most of the properties of nanocrystals embedded in dielectrics and located at injection distances from the substrate surface not limited to the direct tunneling regime.

Published
2012
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41. The fabrication of tunable nanoporous oxide surfaces by block copolymer lithography and atomic layer deposition

Author

Michele Perego, Gabriele Seguini, Sylvie Schamm-Chardon, Marco Fanciulli, Celia Castro, A Andreozzi, Luca Lamagna, Laboratorio MDM (IMM-CNR), Consiglio Nazionale delle Ricerche [Roma] (CNR), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), NanoSci-E+ - ANR-08-NSCI-003: NANOBLOCK, ANR-08-NSCI-0003,NANO-BLOCK(2008), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Andreozzi, A, Lamagna, L, Seguini, G, Fanciulli, M, Schamm Chardon, S, Castro, C, and Perego, M

Subjects
[PHYS]Physics [physics], Materials science, Fabrication, Nanoporous, Thin-Films, Mechanical Engineering, Bioengineering, Nanotechnology, 02 engineering and technology, General Chemistry, Substrate (electronics), 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Nanopore, Atomic layer deposition, Mechanics of Materials, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], General Materials Science, Electrical and Electronic Engineering, Thin film, Reactive-ion etching, 0210 nano-technology, Lithography
Abstract

International audience; Patterned nanoscale materials with controllable characteristic feature sizes and periodicity are of considerable interest in a wide range of fields, with various possible applications ranging from biomedical to nanoelectronic devices. Block-copolymer (BC)-based lithography is a powerful tool for the fabrication of uniform, densely spaced nanometer-scale features over large areas. Following this bottom-up approach, nanoporous polymeric films can be deposited on any type of substrate. The nanoporous periodic template can be transferred to the underlying substrate by dry anisotropic etching. Nevertheless the physical sizes of the polymeric mask represent an important limitation in the implementation of suitable lithographic protocols based on BC technology, since the diameter and the center-to-center distance of the pores cannot be varied independently in this class of materials. This problem could be overcome by combining block copolymer technology with atomic layer deposition (ALD): by means of BC-based lithography a nanoporous SiO2 template, with well-reproducible characteristic dimensions, can be fabricated and subsequently used as a backbone for the growth of perfectly conformal thin oxide films by ALD. In this work polystyrene-b-poly(methylmethacrylate) (PS-b-PMMA) BC and reactive ion etching are used to fabricate hexagonally packed 23 nm wide nanopores in a 50 nm thick SiO2 matrix. By ALD deposition of Al2O3 thin films onto the nanoporous SiO2 templates, nanostructured Al2O3 surfaces are obtained. By properly adjusting the thickness of the Al2O3 film the dimension of the pores in the oxide films is progressively reduced, with nanometer precision, from the original size down to complete filling of the pores, thus providing a simple and fast strategy for the fabrication of nanoporous Al2O3 surfaces with well-controllable feature size.

Published
2011
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42. Dynamics of catalyst particle formation and multi-walled carbon nanotube growth in aerosol-assisted catalytic chemical vapor deposition

Author

Celia Castro, Cécile Reynaud, Nedjma Bendiab, Dominique Porterat, Mathieu Pinault, S. Coste-Leconte, Martine Mayne-L’Hermite, Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Systèmes hybrides de basse dimensionnalité (HYBRID), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Systèmes hybrides de basse dimensionnalité (NEEL - HYBRID), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)

Subjects
inorganic chemicals, Nanotube, Vapor pressure, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, Carbon nanotube, 010402 general chemistry, 7. Clean energy, 01 natural sciences, complex mixtures, Catalysis, law.invention, law, Organic chemistry, General Materials Science, technology, industry, and agriculture, General Chemistry, 021001 nanoscience & nanotechnology, equipment and supplies, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Chemical engineering, chemistry, Particle, Carbon nanotube supported catalyst, 0210 nano-technology, Carbon
Abstract

International audience; In aerosol-assisted catalytic chemical vapor deposition (CCVD), the catalyst and carbon precursors are introduced simultaneously in the reactor. Catalyst particles are formed in situ and aligned multi-walled CNTs grow at a high rate. To scale-up the process, it is crucial to understand the chemical transformation of the precursors along the thermal gradient of the reactor, and to correlate nanotube growth with catalyst nanoparticle formation. The products synthesized along a cylindrical CVD reactor from an aerosol composed of ferrocene and toluene, as catalyst and carbon precursor, respectively, were studied. The product surface density and iron content are determined as a function of the location and the iron vapor pressure in the reactor. Samples are analyzed by electron microscopy, X-ray diffraction and Raman spectroscopy. We show the strong influence of the thermal gradient on location and rate of formation of both iron particles and CNTs, and demonstrate that catalyst particles are formed by gas phase homogeneous nucleation with a size which correlates with iron vapor pressure. They are gradually deposited on the reactor walls where nanotubes grow with an efficiency which is varying linearly with catalyst particle density. CNT crystallinity appears very high for a large range of temperature and iron content.

Published
2010
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43. X-ray diffraction study of the evolution of Fe-filled multiwalled carbon nanotubes under pressure

Author

Mathieu Pinault, Celia Castro, Mohamed Mezouar, Martine Mayne-L’Hermite, Julien Cambedouzou, F. Datchi, Vasile Heresanu, Nedjma Bendiab, Pascale Launois, Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Laboratoire Francis PERRIN (LFP - URA 2453), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Diffraction, Nanotube, Materials science, Nanowire, Nanotechnology, Mechanical properties of carbon nanotubes, 02 engineering and technology, Carbon nanotube, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, 01 natural sciences, Electronic, Optical and Magnetic Materials, law.invention, Optical properties of carbon nanotubes, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Condensed Matter::Materials Science, Chemical engineering, Transition metal, law, 0103 physical sciences, X-ray crystallography, 010306 general physics, 0210 nano-technology
Abstract

International audience; We present in situ high pressure X-ray diffraction experiments on multi-walled carbon nanotubes (MWNTs) filled with iron-based nanowires. In addition to our diffraction results, we provide a detailed characterization of our samples in terms of nanotube length, iron contents, nanotube number of walls and radial dimension. Both carbon nanotubes and encapsulated iron-based nanowires were found to be stable under high pressure conditions, in contrast with previous experiments performed on Fe-filled MWNTs where structural transitions of nanotubes and Fe3C nanowires were recorded around 9 GPa. We point out the importance of providing a complete structural characterization of the studied material and we propose an explanation for the contradictory results found in the literature based on different structural characteristics of the samples and on recent results on the non-hydrostaticity of some pressure transmitting media.

Published
2009
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44. International Seminar – Contributions to the Development Agenda on Intellectual Property Rights

Author

Ana Celia Castro and Maria Beatriz Amorim Bohrer

Subjects
Community and Home Care, Patent law, Political science, Developing country, TRIPS architecture, Public administration, Intellectual property, Patent system
Abstract

TRIPS as it stands is against the interests of developing countries, and needsreform. In developing their own patent law, developing countries need to recognizethat there is now near consensus among informed observers that patentlaw and practice have, in some cases, overshot, and need to be reformed. Thatis the burden of the recent NAS/NRC report on “A Patent System for the 21stCentury.

Published
2008
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45. Quantitative analysis of doped/undoped ZnO nanomaterials using laser assisted atom probe tomography: Influence of the analysis parameters

Author

Corine Sartel, Lorenzo Mancini, Xavier Portier, Said Hassani, Vincent Sallet, Nooshin Amirifar, Jonathan Houard, Lorenzo Rigutti, Ahmed Ziani, Celia Castro, Emir Zehani, Etienne Talbot, Rodrigue Lardé, Philippe Pareige, Groupe de physique des matériaux (GPM), Centre National de la Recherche Scientifique (CNRS)-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)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Groupe d'Etude de la Matière Condensée (GEMAC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), 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), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), 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)-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)-Université de Caen Normandie (UNICAEN), 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), 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 Physics and Astronomy, Nanotechnology, 02 engineering and technology, Atom probe, 01 natural sciences, law.invention, Nanomaterials, Condensed Matter::Materials Science, law, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Microelectronics, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010302 applied physics, business.industry, Doping, 021001 nanoscience & nanotechnology, Laser, Evaporation (deposition), Semiconductor, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Atom optics, Optoelectronics, 0210 nano-technology, business
Abstract

International audience; In the last decade, atom probe tomography has become a powerful tool to investigate semiconductor and insulator nanomaterials in microelectronics, spintronics, and optoelectronics. In this paper, we report an investigation of zinc oxide nanostructures using atom probe tomography. We observed that the chemical composition of zinc oxide is strongly dependent on the analysis parameters used for atom probe experiments. It was observed that at high laser pulse energies, the electric field at the specimen surface is strongly dependent on the crystallographic directions. This dependence leads to an inhomogeneous field evaporation of the surface atoms, resulting in unreliable measurements. We show that the laser pulse energy has to be well tuned to obtain reliable quantitative chemical composition measurements of undoped and doped ZnO nanomaterials.

Published
2015
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46. O projeto de habitação e de cidade de Candilis, Josic e Woods para a América do Sul: Proyecto Experimental de Vivienda-Previ, Peru | The housing and city project of Candilis, Josic and Woods for South America: Proyecto Experimental de Vivienda-Previ, Peru

Author

Célia Castro Gonsales and Giulianna Bertinetti

Subjects
alex josic. baixa altura alta densidade. georges candilis. previ. shadrach woods., Architectural engineering. Structural engineering of buildings, TH845-895
Abstract

Em 1966 começa no Peru o Proyecto Experimental de Vivienda que, considerado como representativo da problemática de habitação dos países em vias de desenvolvimento, recebeu apoio econômico da Organização das Nações Unidas. A partir de então, é realizado um concurso envolvendo equipes internacionais e peruanas para o projeto de urbanização de 1.500 unidades que deveria contemplar investigações de tipologias habitacionais flexíveis e com possibilidades de crescimento. Este artigo analisa o projeto da “equipe francesa” formada pelos arquitetos Georges Candilis, Alex Josic e Shadrach Woods, considerando-o como uma oportunidade de síntese de uma experiência projetual e teórica de mais de 10 anos. A análise é realizada tendo como pano de fundo tanto o contexto de crítica à cidade funcionalista e à Carta de Atenas proposta nos Congressos Internacionais de Arquitetura Moderna, como o questionamento do conceito desenvolvimentista envolvendo a construção de grandes conjuntos habitacionais desde os anos cinquenta na Europa e América Latina.

Published
2019
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47. Nitric oxide levels in the anterior chamber of vitrectomized eyes with silicon oil

Author

Paulo Escarião, Sílvio de Biasi, Fernando Carvalho, Eduardo Henrique Araujo, and Célia Castro

Subjects
Óxido nítrico, Estresse oxidativo, Vitrectomia, Óleo de silicone, Glaucoma, Ophthalmology, RE1-994
Abstract

PURPOSE: To investigate the nitric oxide levels in the anterior chamber of eyes who underwent pars plana vitrectomy (PPV) with silicone oil. METHODS: Patients who underwent PPV with silicon oil injection, from february 2005 to august 2007, were selected. Nine patients (nine eyes) participated in the study (five women and four men). Nitric oxide concentration was quantified after the aspiration of aqueous humor samples during the procedure of silicon oil removal. Data such as: oil emulsification; presence of oil in the anterior chamber; intraocular pressure and time with silicone oil were evaluated. Values of p

Published
2013
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48. Nanoscale control of Si nanoparticles within a 2D hexagonal array embedded in SiO2 thin films.

Author

Celia Castro, Gérard BenAssayag, Béatrice Pecassou, Andrea Andreozzi, Gabriele Seguini, Michele Perego, and Sylvie Schamm-Chardon

Subjects
*NANOPARTICLES, *THIN films, *LITHOGRAPHY
Abstract

In this work, we investigate the ability to control Si nanoparticles (NPs) spatially arranged in a hexagonal network of 20 nm wide nanovolumes at controlled depth within SiO2 thin films. To achieve this goal an unconventional lithographic technique was implemented based on a bottom-up approach, that is fully compatible with the existing semiconductor technology. The method combines ultra-low energy ion beam synthesis with nanostructured block-copolymer thin films that are self-assembled on the SiO2 substrates to form a nanoporous template with hexagonally packed pores. A systematic analytical investigation using time of flight-secondary ion mass spectroscopy and low-loss energy filtered transmission electron microscopy demonstrates that by adjusting few fabrication parameters, it is possible to narrow the size distribution of the NPs and to control the number of NPs per nanovolume. Experimental results are critically discussed on the basis of literature data, providing a description of the mechanism involved in the formation of Si NPs. [ABSTRACT FROM AUTHOR]

Published
2017
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49. Direitos de propriedade, estratégia e ambiente institucional

Author

Guilherme Fowler de Avila Monteiro, Decio Zylbersztajn, Ana Celia Castro, Sérgio Giovanetti Lazzarini, Cláudio Antonio Pinheiro Machado Filho, and Maria Sylvia Macchione Saes

Abstract

A presente tese investiga como o Ambiente Institucional influencia o modo de governança de direitos de propriedade e a estratégia das firmas. O estudo divide-se em duas partes. A primeira parte empreende uma investigação teórica que se constitui em três etapas. Primeiro, examina-se o modelo de direitos de propriedade de Barzel (1994, 1997, 2003). Segundo, analisa-se uma abordagem de estratégia competitiva baseada em direitos de propriedade (Property Rights Perspective; Foss e Foss, 2001). Especificamente, argumenta-se que tal abordagem representa uma extensão do modelo de Barzel e demonstra-se que os conceitos introduzidos na etapa anterior possibilitam uma formulação mais geral da Property Rights Perspective, conduzindo a uma definição de estratégia competitiva que concilia as noções de strategizing e economizing (Williamson, 1991). A terceira etapa, por fim, examina particularmente o estabelecimento de estratégias de proteção de direitos de propriedade. Um modelo heurístico baseado em Williamson (1996) é proposto e com base nele três formas básicas de proteção são definidas em função da qualidade do Ambiente Institucional: estratégia centrada no sistema legal, no estabelecimento de mecanismos privados e no abandono de atributos valiosos. A segunda parte da pesquisa busca evidências empíricas que suportem o modelo teórico. O estudo examina três casos de proteção de direitos de propriedade sobre a tecnologia transgênica em sementes de soja: EUA, Brasil e Argentina. Cada um dos casos representa, respectivamente, uma forma de proteção de direitos como definido pelo modelo heurístico. A pesquisa examina também evidências econométricas que consolidam a análise empírica. De forma geral, o presente estudo desenvolve uma abordagem para o exame da apropriação de valor, colocando-se na interface entre a Economia de Direitos de Propriedade, o estudo da Estratégia e a análise do Ambiente Institucional. The current thesis investigates how the Institutional Environment influences the mode of governance of property rights and the strategy of firms. The study is divided into two parts. The first part undertakes a theoretical investigation consisting of three steps. In the first step, the author examines the model of property rights developed by Barzel (1994, 1997, 2003). In the second step, an approach to competitive strategy based on property rights (Property Rights Perspective, Foss and Foss, 2001) is analyzed. Specifically, the author states that this approach represents an extension of Barzels model and demonstrates that the concepts introduced in the previous step allow a more general formulation of the Property Rights Perspective, leading to a definition of competitive strategy that reconciles the notions of strategizing and economizing (Williamson, 1991). The last step examines particularly the establishment of strategies for protection of property rights. A heuristic model based on Williamson (1996) is proposed and three strategies for protection of property rights are defined in terms of the quality of the Institutional Environment: strategy based on the legal system, on the establishment of private mechanisms, and on the abandon of valuable attributes. The second part of the research seeks empirical evidence to support the theoretical model. The study examines three cases of protection of property rights on genetically modified (GM) technology in soybean seeds: the US, Brazil, and Argentina. Each case represents, respectively, a strategy as defined by the heuristic model. The research also examines econometric evidence that consolidate the empirical analysis. Overall, the current study develops an approach for examining the appropriation of value, placing itself in the interface between the Property Rights Economics, the study of Strategy, and the assessment of the Institutional Environment.

Published
2015
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50. Diferenciação e geração de renda nos sistemas agroindustriais

Author

Bruno Varella Miranda, Maria Sylvia Macchione Saes, Ricardo Abramovay, and Ana Celia Castro

Abstract

O presente trabalho discute a relação entre a diferenciação na produção e a geração de renda nos sistemas agroindustriais. Dividido em três artigos, seu objetivo é apresentar uma interpretação para a dificuldade dos produtores rurais de aumentarem sua participação na renda total gerada nessas cadeias. Ao longo das próximas páginas, um aspecto do cotidiano dos agricultores será especialmente debatido, qual seja: o processo de obtenção das informações relativas aos mercados em que participam. Conforme será demonstrado a seguir, nem sempre a diferenciação sucede a plena identificação de uma oportunidade de obtenção de rendas extraordinárias. Pelo contrário, não raramente os custos ligados à busca dessas informações são demasiado altos. Com isso, a diferenciação seria estimulada por agentes capazes de colher esses dados, e que forneceriam incentivos para o estabelecimento de uma relação cooperativa. Tendo em vista a possibilidade de adoção de estratégias oportunistas, porém, tal dependência pode abrir espaço para a ocultação parcial das informações relativas ao valor gerado a partir da especialização produtiva. Por outro lado, a existência de enraizamento social nas relações econômicas poderia contribuir para a transferência de informações aos parceiros comerciais ainda quando sua obtenção fosse improvável. A dificuldade de obtenção dessas informações constituiria um aspecto fundamental na dinâmica dos sistemas agroindustriais inclusive naqueles mercados organizados em torno de uma certificação. Nestes, a obtenção das informações relevantes deveria ser, teoricamente, facilitada aos agentes. The following thesis discusses the relation between productive differentiation and rent generation in agro-industrial systems. Divided in three articles, its goal is to present an interpretation to the difficult of agricultural producers to increase their participation in the total rent created in these chains. In the next pages, one aspect of producers routines will especially be discussed: the process of gathering information relative to the markets in which they take part. In many cases, differentiation processes do not respond to the identification of a business opportunity. Instead, the costs associated to the search of this information are prohibitive for many agents. So, the responsible for the identification of a business opportunity will provide the incentives to other agents, in order to convince them to engage in a specific economic relation. However, agents based on opportunistic motivations may hide part of this information, providing incentives which dont correspond to the right payoff of each contribution. In other hand, the existence of social embeddedness in an economic relationship is a factor which may guarantee the transference of information even when it would be impossible to the agents to search this data by themselves. The problem presented here has a pervasive nature, since it can be found in almost every market.

Published
2015
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