198 results on '"Pere Roca"'
Search Results
2. Evolution of Cu-In Catalyst Nanoparticles under Hydrogen Plasma Treatment and Silicon Nanowire Growth Conditions
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Weixi Wang, Éric Ngo, Pavel Bulkin, Zhengyu Zhang, Martin Foldyna, Pere Roca i Cabarrocas, Erik V. Johnson, and Jean-Luc Maurice
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Cu-In nanoparticle ,plasma treatment ,silicon nanowire ,PECVD ,TEM ,Chemistry ,QD1-999 - Abstract
We report silicon nanowire (SiNW) growth with a novel Cu-In bimetallic catalyst using a plasma-enhanced chemical vapor deposition (PECVD) method. We study the structure of the catalyst nanoparticles (NPs) throughout a two-step process that includes a hydrogen plasma pre-treatment at 200 °C and the SiNW growth itself in a hydrogen-silane plasma at 420 °C. We show that the H2-plasma induces a coalescence of the Cu-rich cores of as-deposited thermally evaporated NPs that does not occur when the same annealing is applied without plasma. The SiNW growth process at 420 °C induces a phase transformation of the catalyst cores to Cu7In3; while a hydrogen plasma treatment at 420 °C without silane can lead to the formation of the Cu11In9 phase. In situ transmission electron microscopy experiments show that the SiNWs synthesis with Cu-In bimetallic catalyst NPs follows an essentially vapor-solid–solid process. By adjusting the catalyst composition, we manage to obtain small-diameter SiNWs—below 10 nm—among which we observe the metastable hexagonal diamond phase of Si, which is predicted to have a direct bandgap.
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- 2023
- Full Text
- View/download PDF
3. Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation
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Zhen Zheng, Junyang An, Ruiling Gong, Yuheng Zeng, Jichun Ye, Linwei Yu, Ileana Florea, Pere Roca i Cabarrocas, and Wanghua Chen
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Kelvin probe force microscopy ,c-Si passivation ,surface potential ,AlOx ,SiOx ,Chemistry ,QD1-999 - Abstract
In this work, we report the same trends for the contact potential difference measured by Kelvin probe force microscopy and the effective carrier lifetime on crystalline silicon (c-Si) wafers passivated by AlOx layers of different thicknesses and submitted to annealing under various conditions. The changes in contact potential difference values and in the effective carrier lifetimes of the wafers are discussed in view of structural changes of the c-Si/SiO2/AlOx interface thanks to high resolution transmission electron microscopy. Indeed, we observed the presence of a crystalline silicon oxide interfacial layer in as-deposited (200 °C) AlOx, and a phase transformation from crystalline to amorphous silicon oxide when they were annealed in vacuum at 300 °C.
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- 2021
- Full Text
- View/download PDF
4. Mechanical compartmentalization of the intestinal organoid enables crypt folding and collective cell migration
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Gerardo Ceada, Marija Matejčić, Andrew G. Clark, Marino Arroyo, Anghara Menendez, Denis Krndija, Venkata Ram Gannavarapu, Pere Roca-Cusachs, Natalia Castro, Manuel Gomez-Gonzalez, Xavier Trepat, Adrián Álvarez-Varela, Francesco Greco, Carlos Pérez-González, Danijela Matic Vignjevic, Sohan Kale, Eduard Batlle, Universitat Politècnica de Catalunya. Centre Específic de Recerca de Mètodes Numèrics en Ciències Aplicades i Enginyeria, Universitat Politècnica de Catalunya. Departament d'Enginyeria Civil i Ambiental, and Universitat Politècnica de Catalunya. LACÀN - Mètodes Numèrics en Ciències Aplicades i Enginyeria
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Biomatemàtica ,Crypt ,Matemàtiques i estadística::Matemàtica aplicada a les ciències [Àrees temàtiques de la UPC] ,Numerical analysis--Simulation methods ,Extracellular matrix ,03 medical and health sciences ,0302 clinical medicine ,Organoid ,Cell migration ,65 Numerical analysis::65C Probabilistic methods, simulation and stochastic differential equations [Classificació AMS] ,030304 developmental biology ,Biomathematics ,Anàlisi numèrica ,Intestins ,0303 health sciences ,Migració cel·lular ,Chemistry ,Matemàtiques i estadística::Anàlisi numèrica::Mètodes numèrics [Àrees temàtiques de la UPC] ,92 Biology and other natural sciences::92B Mathematical biology in general [Classificació AMS] ,Apical constriction ,Cell Biology ,Compartmentalization (psychology) ,Intestinal epithelium ,Cell biology ,Intestines ,Folding (chemistry) ,030220 oncology & carcinogenesis ,Self-healing hydrogels - Abstract
Intestinal organoids capture essential features of the intestinal epithelium such as crypt folding, cellular compartmentalization and collective movements. Each of these processes and their coordination require patterned forces that are at present unknown. Here we map three-dimensional cellular forces in mouse intestinal organoids grown on soft hydrogels. We show that these organoids exhibit a non-monotonic stress distribution that defines mechanical and functional compartments. The stem cell compartment pushes the extracellular matrix and folds through apical constriction, whereas the transit amplifying zone pulls the extracellular matrix and elongates through basal constriction. The size of the stem cell compartment depends on the extracellular-matrix stiffness and endogenous cellular forces. Computational modelling reveals that crypt shape and force distribution rely on cell surface tensions following cortical actomyosin density. Finally, cells are pulled out of the crypt along a gradient of increasing tension. Our study unveils how patterned forces enable compartmentalization, folding and collective migration in the intestinal epithelium.
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- 2021
5. Hydrogen Plasma-Assisted Growth of Gold Nanowires
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Bozhi Tian, Sébastien Duguay, Wanghua Chen, Zhen Zheng, Junyang An, Edy Azrak, Antonino Foti, Simona Moldovan, Philippe Pareige, Chantal Karam, Vishnu Nair, Jean-Luc Maurice, Pere Roca i Cabarrocas, Ruiling Gong, Ningbo University (NBU), 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), 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), University of Chicago, Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Institut Européen des membranes (IEM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-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), Normandie Université (NU), and Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)
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Amorphous silicon ,Materials science ,Silicon ,Nanowire ,chemistry.chemical_element ,Nanotechnology ,engineering.material ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Coating ,Etching (microfabrication) ,General Materials Science ,Dewetting ,[INFO.INFO-BT]Computer Science [cs]/Biotechnology ,Thin film ,ComputingMilieux_MISCELLANEOUS ,010405 organic chemistry ,Photothermal effect ,General Chemistry ,Condensed Matter Physics ,3. Good health ,0104 chemical sciences ,chemistry ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,engineering - Abstract
International audience; Because of their innocuity, Au nanowires present an interesting field of applications in biology and, particularly, in cancer therapy. Since their morphology and distribution can greatly affect their performances, being able to control their mode of growth is important. Various elaboration techniques including “top-down” and “bottom-up” approaches have been developed. In this work, we propose an efficient maskless method to grow Au nanowires with the help of hydrogen plasma treatment of Au thin films. We have been able to grow Au nanowires by taking advantage of spinodal dewetting of an Au thin film and the supply of silicon radicals resulting from hydrogen plasma etching of amorphous silicon coating the walls of the reactor. A variety of techniques have been applied to study the microstructure and the optical properties of Au nanowires. A strong photothermal effect of Au nanowires has been demonstrated with the help of visible laser light. In order to study the nanowire growth, the transport of Au atoms is discussed, and a growth mechanism is proposed.
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- 2020
6. Low-Temperature Plasma-Assisted Growth of Core–Shell GeSn Nanowires with 30% Sn
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Sébastien Duguay, Simona Moldovan, Pere Roca i Cabarrocas, Philippe Pareige, Wanghua Chen, Edy Azrak, 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), Ningbo University (NBU), 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)
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Materials science ,Alloy ,Analytical chemistry ,Nanowire ,02 engineering and technology ,Substrate (electronics) ,engineering.material ,010402 general chemistry ,01 natural sciences ,Catalysis ,chemistry.chemical_compound ,Physical and Theoretical Chemistry ,ComputingMilieux_MISCELLANEOUS ,Eutectic system ,Low temperature plasma ,Plasma ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,chemistry ,Germane ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,engineering ,[PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph] ,0210 nano-technology - Abstract
We report on the growth of Sn-catalyzed GeSn nanowires (NWs) having a GeSn core and a c-Ge shell in the presence of germane plasma at substrate temperatures (TS) below the GeSn eutectic temperature (TE), containing an exceptional Sn concentration of 30 at. % in their core. The differences between the NWs produced at TS above and below TE of the GeSn alloy are highlighted. Two types of NW growth process are identified: the previously reported in-plane solid–liquid–solid (IPSLS) process for TS ≥ TE and a plasma-assisted IPSLS (PA-IPSLS) method taking place at TS < TE; the crucial role of plasma in providing the energy necessary to melt the Sn catalyst at substrate temperatures lower than TE is discussed. The thermal activation window for each method is determined. The PA-IPSLS process is shown to provide an efficient strategy for the growth of crystalline GeSn NWs with a high Sn incorporation in a growth duration of less than 3 min.
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- 2019
7. Competition for endothelial cell polarity drives vascular morphogenesis
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Daniela Ramalho, I. Mauldin, I. Fortunato, L. H. Misikova, D. Barata, M. Dominguez-Cejudo, Miguel O. Bernabeu, Yulia Carvalho, Anna Pezzarossa, Catarina G Fonseca, Andreia Pena, Anne Eichmann, Pere Roca-Cusachs, Ylenia Giarratano, L. M. Faure, Xavier Trepat, Claudio A. Franco, M. Ouarne, Manuel Gomez-Gonzalez, Georgia Zarkada, and Pedro Miguel Branco Barbacena
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Sprouting angiogenesis ,History ,Polymers and Plastics ,Chemistry ,Polarity (physics) ,Industrial and Manufacturing Engineering ,Cell biology ,Adherens junction ,Endothelial stem cell ,Focal adhesion ,Vascular endothelial growth factor A ,medicine.anatomical_structure ,Cell polarity ,medicine ,Business and International Management ,Blood vessel - Abstract
Blood vessel formation generates unique vascular patterns in each individual. The principles governing the apparent stochasticity of this process remain to be elucidated. Using mathematical methods, we find that the transition between two fundamental vascular morphogenetic programs – sprouting angiogenesis and vascular remodeling – is established by a shift on collective front-rear polarity of endothelial cells. We demonstrate that the competition between biochemical (VEGFA) and mechanical (blood flow-induced shear stress) cues controls this collective polarity shift. Shear stress increases tension at focal adhesions overriding VEGFA-driven collective polarization, which relies on tension at adherens junctions. We propose that vascular morphogenetic cues compete to regulate individual cell polarity and migration through tension shifts that translates into tissue-level emergent behaviors, ultimately leading to uniquely organized vascular patterns.
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- 2021
8. Liquid-assisted vapor-solid-solid silicon nanowire growth mechanism revealed by in situ TEM when using Cu-Sn bimetallic catalysts
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Pere Roca i Cabarrocas, Pavel Bulkin, Jean-Luc Maurice, Martin Foldyna, Weixi Wang, Ileana Florea, Eric Ngo, Institut de Chimie et des Matériaux Paris-Est (ICMPE), Institut de Chimie du CNRS (INC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-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), ANR-17-CE09-0011,HexaNW,Croissance vapeur-liquide-solide de nanofils de silicium de phase hexagonale diamant(2017), and ANR-10-EQPX-0050,TEMPOS,Microscopie electronique en transmission sur le plateau Palaiseau Orsay Saclay(2010)
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In situ ,Materials science ,Silicon ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,7. Clean energy ,01 natural sciences ,Silane ,Dissociation (chemistry) ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Catalysis ,chemistry.chemical_compound ,General Energy ,Chemical engineering ,chemistry ,Transmission electron microscopy ,0103 physical sciences ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Molecule ,Physical and Theoretical Chemistry ,010306 general physics ,0210 nano-technology ,Bimetallic strip - Abstract
International audience; The vapor-liquid-solid (VLS) and vapor-solid-solid (VSS) growth mechanisms are widely used to obtain silicon nanowires. In this paper, we report on a hybrid method based on the use of a dual-phase catalyst made of liquid Sn and solid Cu 3 Si, which results in a liquid-assisted VSS (LA-VSS) mechanism. The silicon atoms are brought by atomic hydrogen-assisted dissociation of silane molecules. We observe the growth in situ, in the transmission electron microscope, at
- Published
- 2021
9. A mechanosensing mechanism mediated by IRSp53 controls plasma membrane shape homeostasis at the nanoscale
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Andrea Disanza, Francesc Tebar, Giorgio Scita, Marino Arroyo, Alexandra Mittens, Xavier Trepat, Nikhil Walani, Anabel-Lise Le Roux, Xarxa Quiroga, Robert G. Parton, Pere Roca-Cusachs, Albert Chavero, and María Isabel Geli
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Membrane ,Evagination ,Polymerization ,Chemistry ,Biophysics ,RAC1 ,Plasma ,Nanoscopic scale ,Actin ,Homeostasis - Abstract
As cells migrate and experience forces from their surroundings, they constantly undergo mechanical deformations which reshape their plasma membrane (PM). To maintain homeostasis, cells need to detect and restore such changes, not only in terms of overall PM area and tension as previously described, but also in terms of local, nano-scale topography. Here we describe a novel phenomenon, by which cells sense and restore mechanically induced PM nano-scale deformations. We show that cell stretch and subsequent compression reshape the PM in a way that generates local membrane evaginations in the 100 nm scale. These evaginations are recognized by the I-BAR protein IRSp53, which triggers a burst of actin polymerization mediated by Rac1 and Arp2/3. The actin polymerization burst subsequently re-flattens the evagination, completing the mechanochemical feedback loop. Our results demonstrate a new mechanosensing mechanism for PM shape homeostasis, with potential applicability in different physiological scenarios.TeaserCell stretch cycles generate PM evaginations of ≈100 nm which are sensed by IRSp53, triggering a local event of actin polymerization that flattens and recovers PM shape.
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- 2021
10. An E-cadherin-actin clutch translates the mechanical force of cortical flow for cell-cell contact to inhibit epithelial cell locomotion
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Ivar Noordstra, Mario Díez Hermoso, Lilian Schimmel, Alexis Bonfim-Melo, Denni Currin-Ross, Cao Nguyen Duong, Joseph Mathew Kalappurakkal, Richard G. Morris, Dietmar Vestweber, Satyajit Mayor, Emma Gordon, Pere Roca Cusachs, and Alpha S. Yap
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Adherens junction ,Cadherin ,Chemistry ,Biophysics ,Clutch ,Catch bond ,Mechanosensitive channels ,Adhesion ,Actin ,Cortex (botany) - Abstract
SUMMARYAdherens junctions allow cell contact to inhibit epithelial migration. But a long-standing puzzle is how locomotion is downregulated when E-cadherin adhesions form at surfaces perpendicular, but not those parallel, to the direction of migration. We now show that this arises from coupling between E-cadherin adhesions and the retrograde cortical flows of leader cells in migrating epithelia. At interfaces perpendicular to the direction of motion, such flows are antiparallel, which generates a tensile signal that induces the actin-binding domain of α-catenin to promote lateral growth of nascent adhesions and inhibit the lamellipodial activity necessary for migration. At interfaces parallel to the direction of motion, by contrast, cortical flows are aligned and no such mechanical inhibition takes place. Therefore, α-catenin mechanosensitivity in the clutch between E-cadherin and cortical F-actin allows cells to interpret the direction of motion via cortical flows and trigger the first signal for contact to inhibit locomotion.
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- 2021
11. Mechanosensitivity of nucleocytoplasmic transport
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Alberto Elosegui-Artola, Amy E. M. Beedle, Xavier Trepat, Ion Andreu, Ignasi Granero, Pere Roca-Cusachs, Barak Raveh, Nimesh Chahare, Kessem Clein, and Marc Molina Jordan
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medicine.anatomical_structure ,Signalling ,Facilitated diffusion ,Chemistry ,Nucleocytoplasmic Transport ,Biophysics ,medicine ,Nuclear force ,Nuclear transport ,Nuclear pore ,Nucleus ,Nuclear localization sequence - Abstract
Mechanical force controls fundamental cellular processes in health and disease, and increasing evidence shows that the nucleus both experiences and senses applied forces. Here we show that nuclear forces differentially control passive and facilitated nucleocytoplasmic transport, setting the rules for the mechanosensitivity of shuttling proteins. We demonstrate that nuclear force increases permeability across nuclear pore complexes, with a dependence on molecular weight that is stronger for passive than facilitated diffusion. Due to this differential effect, force leads to the translocation into or out of the nucleus of cargoes within a given range of molecular weight and affinity for nuclear transport receptors. Further, we show that the mechanosensitivity of several transcriptional regulators can be both explained by this mechanism, and engineered exogenously by introducing appropriate nuclear localization signals. Our work sets a novel framework to understand mechanically induced signalling, with potential general applicability across signalling pathways and pathophysiological scenarios.One sentence summaryForce application to the nucleus leads to nuclear accumulation of proteins by differentially affecting passive versus facilitated nucleocytoplasmic transport.
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- 2021
12. Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation
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Wanghua Chen, Zhen Zheng, Ileana Florea, Ruiling Gong, Pere Roca i Cabarrocas, Junyang An, Linwei Yu, Jichun Ye, Yuheng Zeng, Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)
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Amorphous silicon ,Materials science ,surface potential ,Passivation ,General Chemical Engineering ,AlOx ,c-Si passivation ,02 engineering and technology ,Kelvin probe force microscopy ,01 natural sciences ,chemistry.chemical_compound ,0103 physical sciences ,General Materials Science ,Wafer ,Crystalline silicon ,[INFO.INFO-BT]Computer Science [cs]/Biotechnology ,High-resolution transmission electron microscopy ,QD1-999 ,ComputingMilieux_MISCELLANEOUS ,SiOx ,010302 applied physics ,Kelvin probe force microscope ,business.industry ,AlO x ,Carrier lifetime ,021001 nanoscience & nanotechnology ,Chemistry ,chemistry ,Optoelectronics ,SiO x ,sense organs ,0210 nano-technology ,business ,Volta potential - Abstract
In this work, we report the same trends for the contact potential difference measured by Kelvin probe force microscopy and the effective carrier lifetime on crystalline silicon (c-Si) wafers passivated by AlOx layers of different thicknesses and submitted to annealing under various conditions. The changes in contact potential difference values and in the effective carrier lifetimes of the wafers are discussed in view of structural changes of the c-Si/SiO2/AlOx interface thanks to high resolution transmission electron microscopy. Indeed, we observed the presence of a crystalline silicon oxide interfacial layer in as-deposited (200 °C) AlOx, and a phase transformation from crystalline to amorphous silicon oxide when they were annealed in vacuum at 300 °C.
- Published
- 2021
13. Firmly standing three-dimensional radial junctions on soft aluminum foils enable extremely low cost flexible thin film solar cells with very high power-to-weight performance
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Xiaolin Sun, Junzhuan Wang, Yi Shi, Ting Zhang, Pere Roca i Cabarrocas, Linwei Yu, Ling Xu, Jun Xu, Fan Yang, and Kunji Chen
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Amorphous silicon ,Materials science ,Diffusion barrier ,Nanowire ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,Coating ,law ,Solar cell ,General Materials Science ,Electrical and Electronic Engineering ,Thin film ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,engineering ,Optoelectronics ,0210 nano-technology ,business ,Layer (electronics) - Abstract
Flexibility and power-to-weight (PTW) ratio are the key factors for promoting wearable or portable solar cell applications. Planar hydrogenated amorphous silicon (a-Si:H) thin films deposited directly on soft aluminum foils (AF) are usually subject to easy cracking and delamination due to the mechanical instability on AF surface. Here, an exceptionally robust three-dimensional (3D) construction of a-Si:H radial p-i-n junction solar cells on soft supermarket-available AF of 15 µm thick is reported, where the discrete and firmly standing Si nanowire (SiNW) cores, grown and rooted on the soft AF surface, frame up a 3D architecture that protects the protrusive photo-active radial junctions from the unstable a-Si/Al bottom layer. An excellent flexibility and integrity of the 3D a-Si:H radial junctions have been achieved, even under bending to radius of 5 mm. Remarkably, without any diffusion barrier protection, a power conversion efficiency of 5.6% has been recorded, with an open-circuit voltage of 0.71 V and photo-current density of 14.2 mA/cm2, leading to a high PTW ratio of > 1300 W/kg. Importantly, the overall fabrication cost can be largely slashed off, by ~46% compared to conventional a-Si:H solar cells, as the need for a bottom TCO contact/texturing layer, for a back-reflection coating and for a glass/polymer substrate are all exempted.
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- 2018
14. Advances in the development of high efficiency III-V multijunction solar cells on Ge|Si virtual substrates
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Pere Roca i Cabarrocas, Victor Orejuela, Manuel Hinojosa, Monalisa Ghosh, Iván García, Clara Sanchez, Shabnam Dadgostar, and Ignacio Rey-Stolle
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Silicon ,Materials science ,business.industry ,Germanium ,Triple junction ,Germanio ,chemistry.chemical_element ,Multijunction photovoltaic cell ,Silicio ,Células fotovoltaicas multiunión ,chemistry ,Optoelectronics ,Multijunction solar cells ,business ,Absorption (electromagnetic radiation) ,Porosity ,Layer (electronics) ,Deposition (law) - Abstract
Producción Científica, Virtual Ge substrates fabricated by direct deposition of Ge on Si have become a pathway with high potential to attain high-efficiency III-V multijunction solar cells on Si. We study the development of III-V triple junction solar cells using two types of Ge|Si virtual substrates. The first uses a thick (2-5 μm) Ge layer grown by CVD, which acts as the bottom Ge subcell. The second, grown by low-temperature RT-PECVD, has a thickness of a few tens of nanometres, with the Si substrate acting as Si bottom cell. We discuss the challenges related to each design (formation of cracks, parasitic absorption in the Ge layer, dislocations, ...), present the theoretical design and show the experimental results obtained. Finally, an advanced approach using embedded porous Si layers as buffer layers for crack mitigation is also presented., Ministerio de Ciencia, Innovación y Universidades (project RTI2018-094291-B-I00), Comunidad de Madrid (project S2018/EMT-4308), Ministerio de Ciencia e Innovación (grant PRE2019-088437), Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (project VA283P18)
- Published
- 2021
15. Mechanical compartmentalization of the intestinal organoid enables crypt folding and collective cell migration
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Adrián Álvarez-Varela, Sohan Kale, Marija Matejčić, Xavier Trepat, Manuel Gomez-Gonzalez, Pere Roca-Cusachs, Eduard Batlle, Natalia Castro, Carlos Pérez-González, Marino Arroyo, Gerardo Ceada, Francesco Greco, and Danijela Matic Vignjevic
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0303 health sciences ,Cell type ,Chemistry ,digestive, oral, and skin physiology ,Crypt ,Apical constriction ,Compartmentalization (psychology) ,Intestinal epithelium ,Folding (chemistry) ,03 medical and health sciences ,0302 clinical medicine ,Organoid ,Biophysics ,Mitosis ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
Intestinal organoids capture essential features of the intestinal epithelium such as folding of the crypt, spatial compartmentalization of different cell types, and cellular movements from crypt to villus-like domains. Each of these processes and their coordination in time and space requires patterned physical forces that are currently unknown. Here we map the three-dimensional cell-ECM and cell-cell forces in mouse intestinal organoids grown on soft hydrogels. We show that these organoids exhibit a non-monotonic stress distribution that defines mechanical and functional compartments. The stem cell compartment pushes the ECM and folds through apical constriction, whereas the transit amplifying zone pulls the ECM and elongates through basal constriction. Tension measurements establish that the transit amplifying zone isolates mechanically the stem cell compartment and the villus-like domain. A 3D vertex model shows that the shape and force distribution of the crypt can be largely explained by cell surface tensions following the measured apical and basal actomyosin density. Finally, we show that cells are pulled out of the crypt along a gradient of increasing tension, rather than pushed by a compressive stress downstream of mitotic pressure as previously assumed. Our study unveils how patterned forces enable folding and collective migration in the intestinal crypt.
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- 2020
16. Advanced PECVD Processes for SiNW Based Solar Cells and Thin Film Transistors
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Pere Roca i Cabarrocas and Linwei Yu
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Materials science ,Silicon ,business.industry ,chemistry.chemical_element ,Substrate (electronics) ,engineering.material ,Amorphous solid ,Polycrystalline silicon ,chemistry ,Plasma-enhanced chemical vapor deposition ,Thin-film transistor ,engineering ,Optoelectronics ,Crystalline silicon ,Thin film ,business - Abstract
Silicon thin film technology has been driven by hydrogenated amorphous and microcrystalline silicon thin films which are routinely produced using silane plasmas. While SiH 3 is often considered as the main radical for the obtaining of such films, we have shown that changing the process to conditions where silicon clusters and nanocrystals are produced in the plasma can lead to high deposition rates and improved materials, such as hydrogenated polymorphous silicon and polycrystalline silicon [1]. Moreover, by changing the substrate from glass to crystalline silicon, it is possible to produce epitaxial crystalline silicon films (c-Si:H) which can be transferred to foreign substrates to make ultrathin crystalline silicon solar cells [2], [3]. Interestingly enough the structure of these films is found to be tetragonal, indicative of their particular growth process [4]. Even more interesting, this low temperature epitaxial process can be extended to doped films as well as to germanium and SiGe alloys and their heteroepitaxial growth on GaAs [5]. Last but not least, combining PECVD with low melting temperature metal nanoparticles such as indium and tin opens the way to the growth of nanowires (including Ge, Si and GeSn), which allow to achieve efficient light trapping and carrier collection in radial junction solar cells [6] or even to growth in-plane c-Si nanowires for stretchable electronics and photonics applications [7], [8].
- Published
- 2020
17. Transmission electron microscopy characterization of low temperature boron doped silicon epitaxial films
- Author
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Etienne Drahi, Bénédicte Warot-Fonrose, Pere Roca i Cabarrocas, Patricia de Coux, Marta Chrostowski, Melvyn Larranaga, Guillaume Noircler, 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), Interférométrie, In situ et Instrumentation pour la Microscopie Electronique (CEMES-I3EM), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Physique de la Plasticité et Métallurgie (CEMES-PPM), Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), and Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3)
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010302 applied physics ,Materials science ,Silicon ,business.industry ,Annealing (metallurgy) ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Chemical vapor deposition ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Epitaxy ,01 natural sciences ,Ion implantation ,chemistry ,Transmission electron microscopy ,Plasma-enhanced chemical vapor deposition ,0103 physical sciences ,Optoelectronics ,General Materials Science ,[INFO.INFO-BT]Computer Science [cs]/Biotechnology ,0210 nano-technology ,business ,High-resolution transmission electron microscopy ,ComputingMilieux_MISCELLANEOUS - Abstract
Transmission electron microscopy (TEM) techniques can provide a complementary understanding of the physico-chemical mechanisms of the growth and the annealing behavior of boron-doped hydrogenated silicon epitaxial films grown at low temperatures (
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- 2020
18. In Situ Modulated PhotoLuminescence For Process Optimization Of Crystalline Silicon Passivation
- Author
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B. Bazer-Bachi, Ileana Florea, Jorge Posada, François Silva, Anatole Desthieux, Etienne Drahi, Jean-Charles Vanel, Pavel Bulkin, Pere Roca i Cabarrocas, and Mengkoing Sreng
- Subjects
Photoluminescence ,Materials science ,Passivation ,Silicon ,Annealing (metallurgy) ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Carrier lifetime ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry ,Plasma-enhanced chemical vapor deposition ,Wafer ,Crystalline silicon ,0210 nano-technology - Abstract
Modulated Photoluminescence (MPL) is a powerful tool for measuring the minority carrier lifetime of solar cells. An in house in situ MPL equipped Plasma Enhanced Chemical Vapor Deposition reactor enables the monitoring of passivation properties of solar cells during the fabrication steps of devices. In this study, this tool was used to analyze the impact of annealing steps on passivation properties. First, samples passivated by an aluminum oxide layer were annealed and the evolution of the effective lifetime in the wafer was studied. This allowed to optimize the temperature and duration of the heat treatment. A similar study was made on Fired Passivating Contacts with a passivating stack of SiO x /(p) $\mu\mathrm{c}$ -Si:H/SiN x :H. An interesting low-lifetime regime is consistently observed when the samples undergo a high temperature ( $\mathrm{T} > 350^{\circ}\mathrm{C}$ ) annealing step, followed by a lifetime recovery during the subsequent cooling step. Corona charge and TEM images allowed to get a deeper understanding of the passivation mechanisms evidenced during in situ MPL measurements.
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- 2020
19. Nuclear deformation mediates liver cell mechanosensing in cirrhosis
- Author
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Sergi Guixé-Muntet, Constantino Fondevila, Jordi Gracia-Sancho, Sonia Selicean, Jaime Bosch, Jenny Z. Kechagia, Ion Andreu, Martí Ortega-Ribera, Cong Wang, Jean-François Dufour, Annalisa Berzigotti, and Pere Roca-Cusachs
- Subjects
Cell type ,Cirrhosis ,DN-KASH, dominant negative nesprin peptide containing a KASH domain ,Population ,LSEC, liver sinusoidal endothelial cell ,610 Medicine & health ,HSC ,Chronic liver disease ,HNF4α, hepatocyte nuclear factor 4α ,Stiffness ,Lamb1, laminin b1 ,α-SMA, α-smooth muscle actin ,Extracellular matrix ,03 medical and health sciences ,0302 clinical medicine ,Internal Medicine ,medicine ,Immunology and Allergy ,Hepatocyte ,lcsh:RC799-869 ,LSEC ,ACLD, advanced chronic liver disease ,education ,030304 developmental biology ,0303 health sciences ,education.field_of_study ,TAA, thioacetamide ,Hepatology ,Chemistry ,Liver cell ,Gastroenterology ,eNOS, endothelial nitric oxide synthase ,KASH, Klarsicht/abnormal nuclear anchorage-1/Syne homology ,medicine.disease ,HSC, hepatic stellate cell ,3. Good health ,Cell biology ,ECM, extracellular matrix ,medicine.anatomical_structure ,Cd, cytoskeleton disruptor ,Hepatic stellate cell ,lcsh:Diseases of the digestive system. Gastroenterology ,030211 gastroenterology & hepatology ,Research Article - Abstract
Background & Aims Liver stiffness is increased in advanced chronic liver disease (ACLD) and accurately predicts prognosis in this population. Recent data suggest that extracellular matrix stiffness per se may modulate the phenotype of liver cells. We aimed at investigating the effect of matrix stiffness on the phenotype of liver cells of rats with cirrhosis, assessing its influence on their response to antifibrotic strategies and evaluating associated molecular mechanisms. Methods Hepatocytes, hepatic stellate cells, and liver sinusoidal endothelial cells were isolated from healthy rats or rats with cirrhosis (carbon tetrachloride or thioacetamide), and cultured on polyacrylamide gels with different physiologically relevant stiffness for 72 h. Results All cell types of rats with cirrhosis cultured at low stiffness showed a significant phenotype amelioration vs. rigid matrix (assessed by quantitative morphology, mRNA expression, protein synthesis, and electron microscopy imaging). Additionally, stiffness modified the antifibrotic effects of liraglutide in stellate cells of rats with cirrhosis. Finally, evaluation of nuclear morphology revealed that high stiffness induced nuclei deformation in all cell types, an observation confirmed in cells from human livers. Disconnecting the nucleus from the cytoskeleton by cytoskeleton disruption or a defective form of nesprin 1 significantly recovered spherical nuclear shape and quiescent phenotype of cells. Conclusions The environment's stiffness per se modulates the phenotype of healthy rats and liver cells of rats with cirrhosis by altering the nuclear morphology through cytoskeleton-derived mechanical forces. The reversibility of this mechanism suggests that targeting the stiffness-mediated intracellular mechanical tensions may represent a novel therapeutic strategy for ACLD. Lay summary During cirrhosis, the liver becomes scarred, stiff, and unable to perform its normal functions efficiently. In this study, we demonstrated that cells from diseased (stiff) livers recovered their functionality when placed in a soft environment (as that of a healthy liver). Furthermore, treatments aimed at tricking liver cells into believing they are in a healthy, soft liver improved their function and could potentially contribute to treat cirrhosis., Graphical abstract, Highlights • Low stiffness directly improves the phenotype of hepatocytes, hepatic stellate cells, and liver sinusoidal endothelial cells. • Stiffness modulates sinusoidal crosstalk in advanced chronic liver disease (ACLD). • Stiffness may determine the efficacy of antifibrotic strategies. • Mechanical forces applied to the nucleus through the LINC complex mediate the effects of stiffness on liver cell phenotype.
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- 2020
20. Germanium quantum dot infrared photodetectors addressed by self-aligned silicon nanowire electrodes
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Yi Shi, Lingfei Li, Shuaishuai Liu, Linwei Yu, Yaolong Zhao, Pere Roca i Cabarrocas, Jun Xu, Kunji Chen, Junzhuan Wang, Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)
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Materials science ,Nanowire ,chemistry.chemical_element ,Photodetector ,Bioengineering ,Germanium ,02 engineering and technology ,Photodetection ,010402 general chemistry ,01 natural sciences ,Responsivity ,General Materials Science ,Electrical and Electronic Engineering ,[INFO.INFO-BT]Computer Science [cs]/Biotechnology ,ComputingMilieux_MISCELLANEOUS ,business.industry ,Mechanical Engineering ,Photoconductivity ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Amorphous solid ,chemistry ,Mechanics of Materials ,Quantum dot ,Optoelectronics ,0210 nano-technology ,business - Abstract
Germanium quantum dots (GeQDs), addressed by self-aligned and epitaxial silicon nanowires (SiNWs) as electrodes, represent the most fundamental and the smallest units that can be integrated into Si optoelectronics for 1550 nm wavelength detection. In this work, individual GeQD photodetectors have been fabricated based on a low temperature self-condensation of uniform amorphous Si (a-Si)/a-Ge bilayers at 300 °C, led by rolling indium (In) droplets. Remarkably, the diameter of the GeQD nodes can be independently controlled to achieve wider GeQDs for maximizing infrared absorption with narrower SiNW electrodes to ensure a high quality Ge/Si hetero-epitaxial connection. Importantly, these hetero GeQD/SiNW photodetectors can be deployed into predesigned locations for scalable device fabrication. The photodetectors demonstrate a responsivity of 1.5 mA W−1 and a photoconductive gain exceeding 102 to the communication wavelength signals, which are related to the beneficial type-II Ge/Si alignment, gradient Ge/Si epitaxial transition and a larger QD/NW diameter ratio. These results indicate a new approach to batch-fabricate and integrate GeQDs for ultra-compact Si-compatible photodetection and imaging applications.
- Published
- 2020
21. Growth Study of Silicon Nanowires Synthesized Via Plasma-Assisted VLS Using Tin Catalysts
- Author
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F. Kail, L. Chahed, Pere Roca i Cabarrocas, and Siham Djoumi
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Materials science ,Chemical engineering ,chemistry ,chemistry.chemical_element ,Substrate (chemistry) ,Plasma ,Silicon nanowires ,Tin ,Catalysis - Published
- 2020
22. Electrical scanning probe microscopy approaches to investigate solar cell junctions and devices
- Author
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Jean-Paul Kleider, Letian Dai, Clément Marchat, Raphaël Cabal, Pere Roca I. Cabarrocas, Audrey Morisset, José Alvarez, Laboratoire Génie électrique et électronique de Paris (GeePs), CentraleSupélec-Sorbonne Université (SU)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut Photovoltaïque d’Ile-de-France (ITE) (IPVF), Institut National de L'Energie Solaire (INES), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)
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Amorphous silicon ,KPFM ,Materials science ,Silicon ,Surface photovoltage ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,law.invention ,[SPI.MAT]Engineering Sciences [physics]/Materials ,chemistry.chemical_compound ,law ,SPV ,Solar cell ,Crystalline silicon ,[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics ,Silicon oxide ,silicon heterojunctions ,business.industry ,Doping ,C-AFM ,[SPI.NRJ]Engineering Sciences [physics]/Electric power ,Heterojunction ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,silicon nanowires (SiNW) ,chemistry ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,[SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic ,Optoelectronics ,passivated contact ,0210 nano-technology ,business ,polysilicon - Abstract
International audience; C-AFM and KPFM techniques have been applied to investigate advanced junctions that are currently involved in highly efficient silicon solar cells. Our first study focuses on silicon heterojunctions and notably hydrogenated amorphous silicon (a-Si:H)/crystalline silicon (c-Si) P/n or N/p heterostructures which band bending at the interface forms a 2D channel. This conductive channel was indeed evidenced for the first time by cross-sectional investigations by C-AFM confirming the analysis of macroscopic planar conductance measurements. A second example of nanoscale characterization concerns the passivating selective contacts consisting in a thin silicon oxide (SiOx) layer between the c-Si and a highly doped polysilicon (poly-Si) layer. The electrical carrier transport is here not limited by the oxide layer and it is assumed that tunnelling through the oxide and/or the presence of pinholes are the main competitive mechanisms. For this specific heterostructure KPFM reveals local surface potential drops of 15-30 mV, which do not exist on samples without SiOx. These potential drops suggest the presence of pinholes that are formed during the poly-Si annealing process performed in the range of 700-900 °C. Finally, in a third study, we concentrate on p-in radial junction (RJ) silicon nanowire (SiNW) devices that are investigated under illumination by KPFM, in the so-called surface photovoltage (SPV) technique. This work focuses on the possibility of extracting the open-circuit voltage (VOC) on single isolated SiNW RJ by local SPV measurements using different AFM tip shapes and illumination directions in order to minimize shadowing effects.
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- 2020
23. Impact of PECVD μc-Si:H deposition on tunnel oxide for passivating contacts
- Author
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Etienne Drahi, Pierre-Philippe Grand, Cédric Broussillou, Gilles Goaer, Muriel Bouttemy, Jorge Posada, Pere Roca i Cabarrocas, Anatole Desthieux, B. Bazer-Bachi, Davina Messou, Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
cast-mono ,Materials science ,Passivation ,lcsh:TJ807-830 ,Oxide ,lcsh:Renewable energy sources ,02 engineering and technology ,engineering.material ,010402 general chemistry ,silicon solar cell ,01 natural sciences ,7. Clean energy ,passivating contact ,chemistry.chemical_compound ,Plasma-enhanced chemical vapor deposition ,pecvd ,Wafer ,passivation ,Electrical and Electronic Engineering ,[INFO.INFO-BT]Computer Science [cs]/Biotechnology ,Silicon oxide ,ComputingMilieux_MISCELLANEOUS ,Renewable Energy, Sustainability and the Environment ,business.industry ,Doping ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,silicon oxide ,Polycrystalline silicon ,Silicon nitride ,chemistry ,μc-si:h ,engineering ,xps ,Optoelectronics ,0210 nano-technology ,business - Abstract
Passivating contacts are becoming a mainstream option in current photovoltaic industry due to their ability to provide an outstanding surface passivation along with a good conductivity for carrier collection. However, their integration usually requires long annealing steps which are not desirable in industry. In this work we study PECVD as a way to carry out all deposition steps: silicon oxide (SiOx), doped polycrystalline silicon (poly-Si) and silicon nitride (SiNx:H), followed by a single firing step. Blistering of the poly-Si layer has been avoided by depositing (p+) microcrystalline silicon (μc-Si:H). We report on the impact of this deposition step on the SiOx layer deposited by PECVD, and on the passivation properties by comparing PECVD and wet-chemical oxide in this hole-selective passivating contact stack. We have reached iVoc > 690 mV on p-type FZ wafers for wet-chemical SiOx\(p+) μc-Si\SiNx:H with no annealing step.
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- 2020
24. In situ observation of droplet nanofluidics for yielding low-dimensional nanomaterials
- Author
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Linwei Yu, Xavier Lafosse, Sophie Bouchoule, Zheng Fan, Stéphane Guilet, Laurent Couraud, Wanghua Chen, Jean-Luc Maurice, Edmond Cambril, Pere Roca i Cabarrocas, Ileana Florea, Centre de Nanosciences et de Nanotechnologies (C2N), and Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
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Amorphous silicon ,Materials science ,Nucleation ,Nanowire ,General Physics and Astronomy ,Nanotechnology ,Crystal growth ,Nanofluidics ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Nanomaterials ,chemistry.chemical_compound ,Coating ,ComputingMilieux_MISCELLANEOUS ,[PHYS]Physics [physics] ,technology, industry, and agriculture ,Surfaces and Interfaces ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry ,engineering ,Wetting ,0210 nano-technology - Abstract
Droplet based micro/nanofluidics has been demonstrated as a versatile tool in a wide range of fields. In particular, seeded growth of planar low-dimensional nanomaterials often relies on crawling metal droplets as catalytic media where nucleation and crystal growth proceed. However, direct observations of nanomaterials growth led by self-propelled droplet transport remain rare, which leaves many open questions on droplet behavior during growth. Here, we report in situ observations of in-plane Si nanowire growth in a transmission electron microscope, where an indium droplet migrates on a silicon nitride membrane coated by a layer of hydrogenated amorphous silicon (a-Si:H), dissolves the a-Si:H coating film on the membrane, and results in the production of a crystalline Si nanowire in its trail. This in situ observation, combined with the geometric investigation of the nanowires, presents nice consistency with de Gennes’ theoretical prediction of reactive wetting induced droplet motion. Interestingly, we recorded a nanoflake-to-nanowire transition when the growth rate was increased by heating the membrane from 350 °C to 400 °C. This work directly unveils rich transport mechanism of catalytic droplets, which are expected to be a new platform for producing diverse low-dimensional nanomaterials and promote their potential applications in nanoscience and technologies.
- Published
- 2022
25. Growth of In-Plane Ge1–xSnx Nanowires with 22 at. % Sn Using a Solid–Liquid–Solid Mechanism
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Sébastien Duguay, Edy Azrak, Wanghua Chen, Pere Roca i Cabarrocas, Philippe Pareige, Shiwen Gao, Simona Moldovan, 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), Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-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)
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Fabrication ,Materials science ,Silicon ,Band gap ,Alloy ,Nanowire ,Nanoparticle ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,01 natural sciences ,[SPI.MAT]Engineering Sciences [physics]/Materials ,0103 physical sciences ,[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics ,Physical and Theoretical Chemistry ,Solubility ,ComputingMilieux_MISCELLANEOUS ,010302 applied physics ,021001 nanoscience & nanotechnology ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,Chemical engineering ,chemistry ,Transmission electron microscopy ,engineering ,0210 nano-technology - Abstract
Germanium–tin alloys have gained strong attention because of their optical and electrical properties and their compatibility with silicon-based technologies. By increasing the Sn content in the alloy, the charge carrier mobility can be improved, and the energy band gap can be transformed from indirect to direct. However, the fabrication of GeSn is a huge challenge as the equilibrium solubility of Sn in Ge is limited to
- Published
- 2018
26. Nanodroplet Hydrodynamic Transformation of Uniform Amorphous Bilayer into Highly Modulated Ge/Si Island-Chains
- Author
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Kunji Chen, Taige Dong, Linwei Yu, Haiguang Ma, Pere Roca i Cabarrocas, Yi Shi, Yaolong Zhao, Junzhuan Wang, and Jun Xu
- Subjects
Kelvin probe force microscope ,Materials science ,Condensed matter physics ,Silicon ,Mechanical Engineering ,Bilayer ,Superlattice ,Nanowire ,chemistry.chemical_element ,Bioengineering ,Germanium ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Amorphous solid ,chemistry ,0103 physical sciences ,General Materials Science ,Thin film ,010306 general physics ,0210 nano-technology - Abstract
Geometric and compositional modulations are the principal parameters of control to tailor the band profile in germanium/silicon (Ge/Si) heteronanowires (NWs). This has been achieved mainly by alternating the feeding precursors during a uniaxial growth of Ge/Si NWs. In this work, a self-automated growth of Ge/Si hetero island-chain nanowires (hiNWs), consisting of wider c-Ge islands connected by thinner c-Si chains, has been accomplished via an indium (In) droplet-mediated transformation of uniform amorphous a-Si/a-Ge bilayer thin films. The surface-running In droplet enforces a circulative hydrodynamics in the nanoscale droplet, which can modulate the absorption depth into the amorphous bilayer and enable a single-run growth of a superlattice-like hiNWs without the need for any external manipulation. Meanwhile, the separation and accumulation of electrons and holes in the phase-modulated Ge/Si superlattice leads to a modulated surface potential profile that can be directly resolved by Kelvin probe force microscopy. This simple self-assembly growth and modulation dynamics can help to establish a powerful new concept or strategy to tailor and program the geometric and compositional profiles of more complex hetero nanowire structures, as promising building blocks to develop advanced nanoelectronics or optoelectronics.
- Published
- 2018
27. Nanostructured back reflectors produced using polystyrene assisted lithography for enhanced light trapping in silicon thin film solar cells
- Author
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Wanghua Chen, Ari Bimo Prakoso, Pere Roca i Cabarrocas, Zeyu Li, Martin Foldyna, Junkang Wang, Chenjin Lu, E. Rusli, School of Electrical and Electronic Engineering, and Nanoelectronics Centre of Excellence
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Amorphous silicon ,Materials science ,02 engineering and technology ,Trapping ,Chemical vapor deposition ,010402 general chemistry ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,law ,Solar cell ,General Materials Science ,Lithography ,Light Trapping ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,Silicon Thin Film ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Electrical and electronic engineering [Engineering] ,Optoelectronics ,Polystyrene ,Current (fluid) ,0210 nano-technology ,business - Abstract
We study light trapping in hydrogenated amorphous silicon thin film solar cells fabricated by plasma-enhanced chemical vapor deposition on various nanostructured back reflectors. The back reflectors are patterned using polystyrene assisted lithography. We have investigated the correlation between the back reflector optical properties and the corresponding solar cell performance. We have introduced double size polystyrene sphere patterned back reflectors and have provided experimental evidence for improved light trapping performance compared to single size polystyrene sphere patterned back reflectors. We have achieved high performing nanostructured amorphous silicon solar cells with an initial power conversion efficiency of 7.53% and over 20% enhancement of the short-circuit current compared with the reference flat solar cell.
- Published
- 2018
28. Molecular clutch drives cell response to surface viscosity
- Author
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Manuel Salmerón-Sánchez, Mark Bennett, Jonathan M. Cooper, Pere Roca-Cusachs, Julien Reboud, Marco Cantini, and Universitat de Barcelona
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0301 basic medicine ,Surface Properties ,Molecular biology ,Diffusion ,Lipid Bilayers ,Cell Cycle Proteins ,Matrix (biology) ,Microscopy, Atomic Force ,Cell Line ,Myoblasts ,Focal adhesion ,Mice ,03 medical and health sciences ,Viscosity ,Engineering ,Animals ,surface viscosity ,Clutch ,Mechanotransduction ,Lipid bilayer ,Cell Shape ,Adaptor Proteins, Signal Transducing ,mechanotransduction ,Biologia molecular ,Teixits (Histologia) ,Focal Adhesions ,Multidisciplinary ,Chemistry ,food and beverages ,YAP-Signaling Proteins ,Biological Sciences ,Phosphoproteins ,Actins ,Extracellular Matrix ,Fibronectins ,matrix rigidity ,Biophysics and Computational Biology ,cell differentiation ,Tissues ,030104 developmental biology ,Focal Adhesion Kinase 1 ,Physical Sciences ,Phosphatidylcholines ,Viscositat ,Biophysics ,molecular clutch ,Mechanosensitive channels ,Oligopeptides - Abstract
Significance Tissues are viscoelastic in nature and their physical properties play a fundamental role in development, tumorigenesis, and wound healing. Cell response to matrix elasticity is well understood through a “molecular clutch” which engages when stiffness is sufficiently high to expose binding sites in mechanosensitive proteins. Here we show that cell response to pure viscous surfaces (i.e., with no elastic component) can be explained through the same molecular clutch. Mechanisms used by cells to sense rigidity are more universal and can be used to unveil cell interaction with complex viscoelastic environments. The research presents a tool to understand cells within tissues and in turn opens new avenues to incorporate viscosity into the design of synthetic cellular microenvironments., Cell response to matrix rigidity has been explained by the mechanical properties of the actin-talin-integrin-fibronectin clutch. Here the molecular clutch model is extended to account for cell interactions with purely viscous surfaces (i.e., without an elastic component). Supported lipid bilayers present an idealized and controllable system through which to study this concept. Using lipids of different diffusion coefficients, the mobility (i.e., surface viscosity) of the presented ligands (in this case RGD) was altered by an order of magnitude. Cell size and cytoskeletal organization were proportional to viscosity. Furthermore, there was a higher number of focal adhesions and a higher phosphorylation of FAK on less-mobile (more-viscous) surfaces. Actin retrograde flow, an indicator of the force exerted on surfaces, was also seen to be faster on more mobile surfaces. This has consequential effects on downstream molecules; the mechanosensitive YAP protein localized to the nucleus more on less-mobile (more-viscous) surfaces and differentiation of myoblast cells was enhanced on higher viscosity. This behavior was explained within the framework of the molecular clutch model, with lower viscosity leading to a low force loading rate, preventing the exposure of mechanosensitive proteins, and with a higher viscosity causing a higher force loading rate exposing these sites, activating downstream pathways. Consequently, the understanding of how viscosity (regardless of matrix stiffness) influences cell response adds a further tool to engineer materials that control cell behavior.
- Published
- 2018
29. Deterministic Line-Shape Programming of Silicon Nanowires for Extremely Stretchable Springs and Electronics
- Author
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Yi Shi, Taige Dong, Zhaoguo Xue, Pere Roca i Cabarrocas, Junzhuan Wang, Xianlong Wei, Jun Xu, Mei Sun, Zhiqiang Tang, Kunji Chen, Yaolong Zhao, Qing Chen, and Linwei Yu
- Subjects
010302 applied physics ,Materials science ,business.industry ,Scanning electron microscope ,Mechanical Engineering ,Stretchable electronics ,chemistry.chemical_element ,Bioengineering ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Amorphous solid ,Crystallinity ,chemistry ,0103 physical sciences ,Optoelectronics ,General Materials Science ,Electronics ,Thin film ,0210 nano-technology ,business ,High-resolution transmission electron microscopy ,Indium - Abstract
Line-shape engineering is a key strategy to endow extra stretchability to 1D silicon nanowires (SiNWs) grown with self-assembly processes. We here demonstrate a deterministic line-shape programming of in-plane SiNWs into extremely stretchable springs or arbitrary 2D patterns with the aid of indium droplets that absorb amorphous Si precursor thin film to produce ultralong c-Si NWs along programmed step edges. A reliable and faithful single run growth of c-SiNWs over turning tracks with different local curvatures has been established, while high resolution transmission electron microscopy analysis reveals a high quality monolike crystallinity in the line-shaped engineered SiNW springs. Excitingly, in situ scanning electron microscopy stretching and current-voltage characterizations also demonstrate a superelastic and robust electric transport carried by the SiNW springs even under large stretching of more than 200%. We suggest that this highly reliable line-shape programming approach holds a strong promise to extend the mature c-Si technology into the development of a new generation of high performance biofriendly and stretchable electronics.
- Published
- 2017
30. Highly flexible radial tandem junction thin film solar cells with excellent power-to-weight ratio
- Author
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Linwei Yu, Ting Zhang, Kunji Chen, Pere Roca i Cabarrocas, Jun Xu, Junzhuan Wang, Zongguang Liu, and Shaobo Zhang
- Subjects
Amorphous silicon ,Materials science ,Tandem ,Renewable Energy, Sustainability and the Environment ,business.industry ,Filling factor ,Energy conversion efficiency ,Nanowire ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Plasma-enhanced chemical vapor deposition ,Photovoltaics ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) - Abstract
High power-to-weight ratio (PTWR) is an important figure-of-merit for high performance flexible/portable solar cells. Marrying advanced tandem junction design with three-dimensional (3D) Si nanowire (SiNW) framework enables a promising route to boost the PTWR. In this work, a radial tandem junction (RTJ) thin film solar cell has been demonstrated, for the first time, over SiNWs, which consist of radially deposited p-i-n multilayers with hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon germanium (a-SiGe:H) absorption layers in the outer and the inner junctions, respectively. The strong light trapping within the 3D SiNW framework allows for the use of a very thin a-SiGe:H (~45 nm) absorption layer to harvest efficiently the long wavelengths. The RTJ cells fabricated via a one-pump-down process in a single PECVD chamber, directly upon 15 µm thick aluminum foils demonstrate an excellent flexibility that can bend to 10 mm radius and achieve a record PTWR~1628 W/kg, and accomplish a high open-circuit voltage, filling factor and conversion efficiency of 1.2 V, 61.5% and 8.1% on glass, respectively, substantially improved compared to those accomplished by radial single junction cells. These results highlight the unique potential of 3D radial tandem technology to enable a new generation of high performance and durable flexible photovoltaics.
- Published
- 2021
31. Deleterious electrostatic interaction in silicon passivation stack between thin ALD Al2O3 and its a-SiNX:H capping layer: numerical and experimental evidences
- Author
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Pavel Bulkin, Sergej Filonovich, Pere Roca i Cabarrocas, Raphaël Lachaume, François Silva, Erik Johnson, and Fabien Lebreton
- Subjects
010302 applied physics ,Materials science ,Silicon ,Hydrogen ,Passivation ,business.industry ,chemistry.chemical_element ,Field effect ,Nanotechnology ,02 engineering and technology ,Carrier lifetime ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry ,Stack (abstract data type) ,Plasma-enhanced chemical vapor deposition ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,business ,Layer (electronics) - Abstract
This study focuses on the electrostatic interaction between the ALD Al2O3 passivation layer and the PECVD a-SiNX:H capping layer, while reducing ALD Al2O3 thickness. The first one embeds negative fixed charges while the second is well known to possess a fixed charge density with an opposite polarity. We reduced the Al2O3 thickness from 20 to 2 nm while keeping constant the a-SiNX:H thickness. To increase the magnitude of the field effect passivation provided by Al2O3, we used an original light-induced field effect enhancement strategy. QSS-PC was used to quantify the initial passivation properties. We monitored the evolution of the passivation quality under low-intensity light-soaking until its stabilization. We report here a minority carrier lifetime enhancement up to 900% and surface recombination velocity reduction below 10 cm.s-1. The evidence of field effect compensation at c-Si surface due to a-SiNX:H positive charges has been supported by numerical simulations (SILVACO ATLAS). While keeping the parameters of the a-SiNX:H layer constant, the configuration of the Al2O3 layer (thickness and fixed charge density) were varied. These results allow us to conclude that in order to use thinner Al2O3 passivation layer (2 nm), ideal capping layer has to be free of positive fixed charges and to release enough hydrogen at desired temperature to ensure the chemical passivation.
- Published
- 2017
32. Growth of Tetragonal Si via Plasma-Enhanced Epitaxy
- Author
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Ronan Leal, Gwenaëlle Hamon, Ludovic Largeau, Pere Roca i Cabarrocas, Wanghua Chen, and Jean-Luc Maurice
- Subjects
Diffraction ,Materials science ,Hydrogen ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Epitaxy ,01 natural sciences ,Silane ,Thermal expansion ,0104 chemical sciences ,Condensed Matter::Materials Science ,Tetragonal crystal system ,Crystallography ,chemistry.chemical_compound ,chemistry ,Condensed Matter::Superconductivity ,General Materials Science ,0210 nano-technology ,High-resolution transmission electron microscopy - Abstract
We have been able to synthesize directly the tetragonal Si by low temperature plasma-enhanced chemical vapor deposition using hydrogen and silane as the precursor and carrier gas, respectively. With the optimization of growth conditions, a stable tetragonal epitaxial Si can be grown on a crystalline Si substrate at large scale. By combining X-ray diffraction and high resolution transmission electron microscopy measurements, we found that the epitaxial layer has smaller in-plane but larger out-of-plane lattice parameters as compared to the crystalline substrate. The existence of hydrogen platelets in epitaxy is also observed, which affects the diffraction patterns along that direction. We attribute the formation of tetragonal Si to the hydrogenated-cluster-assisted epitaxy. Other possible reasons including host sites of hydrogen atoms and thermal expansion coefficients are also discussed.
- Published
- 2017
33. Evolution of Microstructure and Incorporation of Excess Hydrogen During the Growth of Hydrogenated Polymorphous Silicon at High Rate
- Author
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Ka-Hyun Kim, Erik Johnson, and Pere Roca i Cabarrocas
- Subjects
0301 basic medicine ,High rate ,Ir absorption ,Materials science ,Silicon ,Hydrogen ,Inorganic chemistry ,Biomedical Engineering ,chemistry.chemical_element ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Microstructure ,03 medical and health sciences ,030104 developmental biology ,chemistry ,General Materials Science ,Silicon nanocrystals ,Excess hydrogen - Abstract
Hydrogenated polymorphous silicon (pm-Si:H) is a material consisting of a small volume fraction of nanocrystals embedded in an amorphous matrix, and which can be grown at high deposition rates by increasing the radio-frequency power. When grown at high deposition rates, pm-Si:H films show a shift of their infrared (IR) absorption stretching band peak to higher wavenumbers and a sudden increase in their optical bandgap. The IR absorption spectrum was analyzed by deconvolution into three bands, including a medium stretching mode positioned at 2030 cm−1, which has been attributed to Si–H bonds at silicon nanocrystal surfaces. Secondary ion mass spectrometry measurements confirmed that an excess of hydrogen is incorporated in pm-Si:H grown at high deposition rate, leading to a sharp increase in the optical bandgap. We suggest that this sharp increase can be used as a simple tool to detect the deterioration of material quality when using high deposition rate processes.
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- 2017
34. NatB-mediated protein N-α-terminal acetylation is a potential therapeutic target in hepatocellular carcinoma
- Author
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Pere Roca-Cusachs, Sara Alve, Marta Lasa, Bruno Sangro, José Ignacio Herrero, Alberto Elosegui-Artola, Leire Neri, Cristina Gazquez, Delia D'Avola, Beatriz Carte, Mercedes Iñarrairaegui, Rafael Aldabe, Jesús Prieto, and Universitat de Barcelona
- Subjects
CDK2 ,Motilitat cel·lular ,0301 basic medicine ,Carcinoma, Hepatocellular ,Tropomyosin ,Cell motility ,Biology ,Transfection ,Càncer de fetge ,Focal adhesion ,Adherens junction ,03 medical and health sciences ,chemistry.chemical_compound ,Cell Movement ,Proteïnes citosquelètiques ,Humans ,cell-cell junctions ,Cytoskeleton ,N-Terminal Acetyltransferase B ,Regulation of gene expression ,Focal Adhesions ,Cell growth ,Liver Neoplasms ,Acetylation ,Adherens Junctions ,Cell Cycle Checkpoints ,Actin cytoskeleton ,Cytoskeletal proteins ,3. Good health ,030104 developmental biology ,Oncology ,chemistry ,cell cycle arrest ,Tumor progression ,Cancer research ,Growth inhibition ,Liver cancer ,Research Paper - Abstract
// Leire Neri 1 , Marta Lasa 1 , Alberto Elosegui-Artola 2 , Delia D'Avola 3, 4 , Beatriz Carte 1 , Cristina Gazquez 1 , Sara Alve 5 , Pere Roca-Cusachs 2, 6 , Mercedes Inarrairaegui 3, 4 , Jose Herrero 3, 4 , Jesus Prieto 1, 3 , Bruno Sangro 3, 4 and Rafael Aldabe 1, 4 1 Gene Therapy and Regulation of Gene Expression Program, Centro de Investigacion Medica Aplicada, Universidad de Navarra, Pamplona, Spain 2 Institute for Bioengineering of Catalonia, Barcelona, Spain 3 Liver Unit, Clinica Universidad de Navarra, Centro de Investigacion Biomedica en Red en el Area Tematica de Enfermedades Hepaticas y Digestivas (Ciberehd), Pamplona, Spain 4 Instituto de Investigacion Sanitaria de Navarra (IdiSNA), Pamplona, Spain 5 Department of Biology, CBMA-Centre of Molecular and Environmental Biology, University of Minho, Campus de Gualtar, Braga, Portugal 6 University of Barcelona, Barcelona, Spain Correspondence to: Rafael Aldabe, email: raldabe@unav.es Keywords: tropomyosin, CDK2, focal adhesions, cell-cell junctions, cell cycle arrest Received: December 21, 2016 Accepted: April 04, 2017 Published: April 21, 2017 ABSTRACT The identification of new targets for systemic therapy of hepatocellular carcinoma (HCC) is an urgent medical need. Recently, we showed that hNatB catalyzes the N-α-terminal acetylation of 15% of the human proteome and that this action is necessary for proper actin cytoskeleton structure and function. In tumors, cytoskeletal changes influence motility, invasion, survival, cell growth and tumor progression, making the cytoskeleton a very attractive antitumor target. Here, we show that hNatB subunits are upregulated in in over 59% HCC tumors compared to non-tumor tissue and that this upregulation is associated with microscopic vascular invasion. We found that hNatB silencing blocks proliferation and tumor formation in HCC cell lines in association with hampered DNA synthesis and impaired progression through the S and the G2/M phases. Growth inhibition is mediated by the degradation of two hNatB substrates, tropomyosin and CDK2, which occurs when these proteins lack N-α-terminal acetylation. In addition, hNatB inhibition disrupts the actin cytoskeleton, focal adhesions and tight/adherens junctions, abrogating two proliferative signaling pathways, Hippo/YAP and ERK1/2. Therefore, inhibition of NatB activity represents an interesting new approach to treating HCC by blocking cell proliferation and disrupting actin cytoskeleton function.
- Published
- 2017
35. Current-induced and light-induced macroscopic changes in thin film solar cells: Device degradation mechanism
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Ka-Hyun Kim, Erik Johnson, and Pere Roca i Cabarrocas
- Subjects
In situ ,Amorphous silicon ,Hydrogen ,Silicon ,chemistry.chemical_element ,02 engineering and technology ,Quantum dot solar cell ,01 natural sciences ,Polymer solar cell ,law.invention ,chemistry.chemical_compound ,Optics ,Optical microscope ,law ,0103 physical sciences ,General Materials Science ,010302 applied physics ,Physics ,Renewable Energy, Sustainability and the Environment ,business.industry ,021001 nanoscience & nanotechnology ,chemistry ,Degradation (geology) ,Optoelectronics ,0210 nano-technology ,business - Abstract
We report on the formation of large voids in hydrogenated polymorphous silicon (pm-Si:H) PIN solar cells upon light-soaking. We could monitor in situ, the formation of macroscopic bubbles and holes during current-induced degradation of the same devices using optical microscopy. Forward bias, leading to a current-injection of 300 mA/cm2, was applied to hydrogenated amorphous silicon (a-Si:H) and pm-Si:H PIN solar cells and series of optical images were taken on the same spot at various steps of current-injection. During the current-injection, the pm-Si:H PIN solar cells experience significant topological changes, which we could not detect in a-Si:H PIN solar cells. These effects were further characterized by complementary ex-situ techniques such as SEM, AFM and spectroscopic ellipsometry.
- Published
- 2017
36. High performance transparent in-plane silicon nanowire Fin-TFTs via a robust nano-droplet-scanning crystallization dynamics
- Author
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Pere Roca i Cabarrocas, Zhaoguo Xue, Kunji Chen, Linwei Yu, Ping Feng, Yi Shi, Jimmy Wang, Mingkun Xu, Jun Xu, and Junzhuan Wang
- Subjects
Electron mobility ,Materials science ,business.industry ,Aperture ,Transistor ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Amorphous solid ,law.invention ,chemistry ,Thin-film transistor ,law ,0103 physical sciences ,Nano ,Optoelectronics ,General Materials Science ,Thin film ,010306 general physics ,0210 nano-technology ,business ,Indium - Abstract
High mobility, scalable and even transparent thin-film transistors (TFTs) are always being pursued in the field of large area electronics. While excimer laser-beam-scanning can crystallize amorphous Si (a-Si) into high mobility poly-Si, it is limited to small areas. We here demonstrate a robust nano-droplet-scanning strategy that converts an a-Si:H thin film directly into periodic poly-Si nano-channels, with the aid of well-coordinated indium droplets. This enables the robust batch-fabrication of high performance Fin-TFTs with a high hole mobility of >100 cm2 V−1 s−1 and an excellent subthreshold swing of only 163 mV dec−1, via a low temperature
- Published
- 2017
37. Quasi-fivefold symmetric electron diffraction patterns due to multiple twinning in silicon thin films grown from hexamethyldisiloxane
- Author
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Farah Haddad, Erik Johnson, Junegie Hong, Prabal Goyal, Jean-Luc Maurice, and Pere Roca i Cabarrocas
- Subjects
Diffraction ,Materials science ,Silicon ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,0104 chemical sciences ,Amorphous solid ,Crystallography ,Microcrystalline ,chemistry ,Electron diffraction ,0210 nano-technology ,Crystal twinning - Abstract
Unusual quasi-fivefold symmetric electron diffraction patterns are observed for silicon thin films grown by plasma-enhanced chemical vapour deposition and containing oxygen and carbon impurities in the range of 0.3–5.5%. These films were grown on crystalline (100) silicon wafers using a liquid precursor, hexamethyldisiloxane (HMDSO), mixed with silane, hydrogen and diborane diluted in argon. The occurrence of this quasi-fivefold symmetry is explained by multiple twinning and imperfect epitaxy. A quantitative method performed on the diffraction patterns is developed to evaluate the number of twin operations. This method is also used to discriminate twin positions from random microcrystalline ones in the diffraction patterns and thus to estimate their respective ratios for different growth conditions. Quite remarkably, the random microcrystalline part remains in the range of a few per cent and the diffracted intensities are the sum of two main contributions: multiple (micro-) twinned and amorphous. Increasing the amount of HMDSO decreases the microtwinned part directly to the benefit of the amorphous part with no significant microcrystalline phase. The causes of twinning are presented and discussed by comparing the observations with the literature; dynamical considerations where the system tends to align {111} planes with the growth direction would explain multiple twinning and, in turn, the fivefold symmetry.
- Published
- 2016
38. Influence of anodic bonding on the surface passivation quality of crystalline silicon
- Author
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Pere Roca i Cabarrocas, Jean-Luc Maurice, Wanghua Chen, Valerie Depauw, and Farah Haddad
- Subjects
Amorphous silicon ,Materials science ,Passivation ,Inorganic chemistry ,02 engineering and technology ,010402 general chemistry ,Oxide thin-film transistor ,complex mixtures ,01 natural sciences ,Monocrystalline silicon ,chemistry.chemical_compound ,Crystalline silicon ,Silicon oxide ,Renewable Energy, Sustainability and the Environment ,technology, industry, and agriculture ,Nanocrystalline silicon ,equipment and supplies ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,stomatognathic diseases ,Chemical engineering ,chemistry ,Anodic bonding ,0210 nano-technology - Abstract
Developing new materials with improved thermal stability is very important as far as the passivation and processing of crystalline silicon solar cells is considered. In this work, we studied two types of hydrogenated silicon based materials (hydrogenated amorphous silicon oxide and hydrogenated microcrystalline silicon oxide) and compared them to the well-established hydrogenated amorphous silicon. We demonstrate the thermal robustness of hydrogenated silicon oxide under anodic bonding conditions (250 °C, 1000 V). The microstructural and composition evolution of passivation layers under anodic bonding was characterized by Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy and secondary ion mass spectrometry. We found that oxygen can inhibit the degradation of the passivation quality under anodic bonding by suppressing the localized interfacial crystallization and re-passivating the interface. When applied to thin-film crystalline silicon solar cells, the excellent thermal robustness of hydrogenated microcrystalline silicon oxide allows to keep a good passivation to the ultrathin c-Si absorbers (1 μm).
- Published
- 2016
39. Traction forces at the cytokinetic ring regulate cell division and polyploidy in the migrating zebrafish epicardium
- Author
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Juan F. Abenza, Xavier Trepat, Lorenzo Albertazzi, Isil Tekeli, Angel Raya, Marina Uroz, Silvia Pujals, Ariadna Marín-Llauradó, Pere Roca-Cusachs, Anna Garcia-Puig, Alberto Elosegui-Artola, Vito Conte, Cell-Matrix Interact. Cardiov. Tissue Reg., Molecular Biosensing for Med. Diagnostics, and Universitat de Barcelona
- Subjects
Cell division ,Cytokinetic ring ,02 engineering and technology ,010402 general chemistry ,SDG 3 – Goede gezondheid en welzijn ,01 natural sciences ,Focal adhesion ,Extracellular matrix ,Polyploidy ,SDG 3 - Good Health and Well-being ,Myosin ,Animals ,General Materials Science ,Càncer ,Zebrafish ,Cytokinesis ,Cancer ,biology ,Chemistry ,Mechanical Engineering ,Collective cell migration ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,biology.organism_classification ,0104 chemical sciences ,Cell biology ,Extracellular Matrix ,Mechanics of Materials ,Divisió cel·lular ,0210 nano-technology ,Pericardium ,Cell Division - Abstract
Epithelial repair and regeneration are driven by collective cell migration and division. Both cellular functions involve tightly controlled mechanical events, but how physical forces regulate cell division in migrating epithelia is largely unknown. Here we show that cells dividing in the migrating zebrafish epicardium exert large cell–extracellular matrix (ECM) forces during cytokinesis. These forces point towards the division axis and are exerted through focal adhesions that connect the cytokinetic ring to the underlying ECM. When subjected to high loading rates, these cytokinetic focal adhesions prevent closure of the contractile ring, leading to multi-nucleation through cytokinetic failure. By combining a clutch model with experiments on substrates of different rigidity, ECM composition and ligand density, we show that failed cytokinesis is triggered by adhesion reinforcement downstream of increased myosin density. The mechanical interaction between the cytokinetic ring and the ECM thus provides a mechanism for the regulation of cell division and polyploidy that may have implications in regeneration and cancer.
- Published
- 2019
40. Advanced radial junction thin film photovoltaics and detectors built on standing silicon nanowires
- Author
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Pere Roca i Cabarrocas, Ting Zhang, Jun Xu, Linwei Yu, Junzhuan Wang, Department of Agricultural Sciences, Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Georgia Institute of Technology [Atlanta]
- Subjects
Amorphous silicon ,Materials science ,Photodetector ,Bioengineering ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,chemistry.chemical_compound ,Planar ,Photovoltaics ,General Materials Science ,Electrical and Electronic Engineering ,Thin film ,Absorption (electromagnetic radiation) ,ComputingMilieux_MISCELLANEOUS ,business.industry ,Mechanical Engineering ,[SPI.NRJ]Engineering Sciences [physics]/Electric power ,Photovoltaic system ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Mechanics of Materials ,Optoelectronics ,Photonics ,0210 nano-technology ,business - Abstract
Three-dimensional (3D) construction of radial junction hydrogenated amorphous silicon (a-Si:H) thin film solar cells on standing silicon nanowires (SiNWs) is a promising strategy to maximize the light harvesting performance and improve the photocarrier collection in an optimized junction configuration. The unique light in-coupling and absorption behaviour in the antenna-like 3D photonic structures also necessitates a set of new theoretical models and simulation tools to design, predict and optimize the photovoltaic performance of radial junction solar cells, which can be rather different from planar junction solar cells. Recently, the performance of radial junction a-Si:H thin film solar cells has progressed steadily to a level comparable or even superior to that of their planar counterparts, with plenty of room for further improvement. This review will first address the growth strategy and critical parameter control of SiNWs produced via a plasma-assisted low-temperature vapour-liquid-solid procedure using low-melting-point metals as the catalyst. Then, the construction of high-performance radial junction thin film solar cells over the standing SiNW matrix, as well as their optimal structural designs, will be introduced. At the end, the new applications of 3D radial junction units will be summarized, which include, for example, the construction of very flexible, low-cost and efficient a-Si:H solar cells with the highest power-to-weight ratio, the demonstration of highly sensitive solar-blind photodetectors operating at the ultraviolet wavelength spectrum and the development of novel biomimetic radial tandem junction photodetectors with an intrinsic red-green-blue (RGB) colour distinguishing capability.
- Published
- 2019
41. Integrin binding dynamics modulate ligand-specific mechanosensing in mammary gland fibroblasts
- Author
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Martina Lerche, Jenny Z. Kechagia, Donald Gullberg, Alberto Elosegui-Artola, Camilo Guzmán, Johanna Ivaska, Pere Roca-Cusachs, Maria Georgiadou, and Emilia Peuhu
- Subjects
Extracellular matrix ,Fibronectin ,Focal adhesion ,biology ,Chemistry ,Integrin ,biology.protein ,Mechanotransduction ,Actin ,Type I collagen ,Cell biology ,Integrin binding - Abstract
SummaryThe link between the modulation of integrin activity and cellular mechanosensing of tissue rigidity, especially on different extracellular matrix ligands, remains poorly understood. Here, we find that primary mouse mammary gland stromal fibroblasts (MSFs) are able to spread efficiently on soft collagen-coated substrates, resembling the soft mammary gland tissue. In addition, MSFs generate high forces and display nuclear YAP at a low matrix stiffness, supported by mature focal adhesions, prominent actin stress fibers, and myosin phosphorylation.We describe that loss of the cytosolic integrin inhibitor, SHARPIN, impedes MSF spreading specifically on soft type I collagen but not on fibronectin. Through quantitative experiments and computational modelling, we find that SHARPIN-deficient MSFs display faster force-induced unbinding of adhesions from collagen-coated beads. Faster unbinding, in turn, impairs force transmission in these cells, particularly, at the stiffness optimum observed for wild-type cells, and increases actin retrograde flow. Mechanistically, we link the impaired mechanotransduction of SHARPIN-deficient cells on collagen to reduced levels of the collagen-binding integrin α11β1. Our results unveil a collagen-specific mechanosensing mechanism and suggest a key function for integrin activity regulation and integrin α11β1 in MSF mechanotransduction.
- Published
- 2019
42. Defect State Analysis in Ion‐Irradiated Amorphous‐Silicon Heterojunctions by HAXPES
- Author
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Pere Roca i Cabarrocas, O. Plantevin, Alice Defresne, Jean-Pascal Rueff, Denis Céolin, Min-I Lee, Antonio Tejeda, Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
010302 applied physics ,Amorphous silicon ,Materials science ,business.industry ,Heterojunction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,7. Clean energy ,Ion ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Optoelectronics ,General Materials Science ,Crystalline silicon ,Irradiation ,0210 nano-technology ,business - Abstract
International audience; The efficiency in HIT (Heterojunction with Intrinsic Thin film) solar cells strongly depends on the passivation of dangling bonds at the a-Si:H/c-Si interface by hydrogen, introduced in the plasma enhanced CVD process. Here in, we study controlled defects that are introduced by Ar ion irradiation. We observe by hard X-ray photoemission spectroscopy (HAXPES) that during Ar ion implantation, Si-H bonds in the a-Si:H layer are broken and become dangling bonds. We quantify the number of dangling bonds in the a-Si:H layer, and we identify the electronic states associated to them, which explains previously observed photoluminescence transitions.
- Published
- 2019
43. Fine tuning the extracellular environment accelerates the derivation of kidney organoids from human pluripotent stem cells
- Author
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Carolina Tarantino, Dobryna Zalvidea, Pere Roca-Cusachs, Juan Carlos Izpisua Belmonte, Nuria Montserrat, Josep M. Campistol, Lucia Fanlo, Elena Garreta, Elisa Martí, Luca Cozzuto, Aleix Gavaldà-Navarro, Roger Oria, Patrícia Rezende do Prado, Xavier Trepat, Carmen Hurtado del Pozo, Agencia Estatal de Investigación (España), European Commission, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, Asociación Española Contra el Cáncer, Fundación 'la Caixa', G. Harold & Leila Y. Mathers Foundation, Helmsley Charitable Trust, National Institutes of Health (US), Universidad Católica de San Antonio (España), and Instituto de Salud Carlos III
- Subjects
Embryonic stem cells ,Pregnancy Trimester, Third ,Cellular differentiation ,Biomaterials – cells ,02 engineering and technology ,Stem cells ,Kidney ,010402 general chemistry ,01 natural sciences ,Regenerative medicine ,Article ,Tissue Culture Techniques ,Biomaterials ,Medicina regenerativa ,Pluripotent stem cells ,Pregnancy ,Organoid ,Humans ,General Materials Science ,Induced pluripotent stem cell ,Chemistry ,Mechanical Engineering ,Cell Differentiation ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Embryonic stem cell ,3. Good health ,0104 chemical sciences ,Cell biology ,Organoids ,Transplantation ,Kinetics ,Chorioallantoic membrane ,Cellular Microenvironment ,Mechanics of Materials ,Female ,Stem cell ,Extracellular Space ,Transcriptome ,0210 nano-technology ,Cèl·lules mare - Abstract
The generation of organoids is one of the biggest scientific advances in regenerative medicine. Here, by lengthening the time that human pluripotent stem cells (hPSCs) were exposed to a three-dimensional microenvironment, and by applying defined renal inductive signals, we generated kidney organoids that transcriptomically matched second-trimester human fetal kidneys. We validated these results using ex vivo and in vitro assays that model renal development. Furthermore, we developed a transplantation method that utilizes the chick chorioallantoic membrane. This approach created a soft in vivo microenvironment that promoted the growth and differentiation of implanted kidney organoids, as well as providing a vascular component. The stiffness of the in ovo chorioallantoic membrane microenvironment was recapitulated in vitro by fabricating compliant hydrogels. These biomaterials promoted the efficient generation of renal vesicles and nephron structures, demonstrating that a soft environment accelerates the differentiation of hPSC-derived kidney organoids., This work has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (StG-2014-640525_REGMAMKID to E.G., P.P., C.T. and N.M. and CoG-616480 to X.T.), the European Commission (project H2020-FETPROACT-01-2016-731957 to X.T. and P.R.-C.), the Spanish Ministry of Economy and Competitiveness/FEDER (BFU2016-77498-P to L.F. and E.M., BFU2015-65074 to X.T., BFU2016-79916-P to P.R.-C., SAF2015-72617-EXP to N.M., SAF2017-89782-R to N.M. and RYC-2014-16242 to N.M.), the Generalitat de Catalunya and CERCA programme (2014-SGR-927 to X.T. and 2017 SGR 1306 to N.M.), Asociación Española contra el Cáncer (AECC CI2016 to L.F. and E.M., LABAE16006 to N.M.). R.O. is supported by an FI fellowship (Generalitat de Catalunya). P.R.-C. is also supported by Obra Social La Caixa. J.C.I.B. is supported by the G. Harold and Leila Y. Mathers Charitable Foundation, the Leona M. and Harry B. Helmsley Charitable Trust (2012-PG-MED002), the Moxie Foundation, the National Institutes of Health (5R21AG055938), the Universidad Católica San Antonio de Murcia and Fundación Dr. Pedro Guillén. C.H.P. is supported by the Bioengineering Excellence of Scientific Training project, cofunded from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 712754 and from the Spanish Ministry of Economy and Competitiveness under the Severo Ochoa grant SEV-2014-0425 (2015–2019). N.M. is also supported by CardioCel (TerCel, Instituto de Salud Carlos III). IBEC is the recipient of a Severo Ochoa Award of Excellence from MINECO.
- Published
- 2019
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44. Annealing of boron-doped hydrogenated crystalline silicon grown at low temperature by PECVD
- Author
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José Alvarez, Simona Binetti, Marta Chrostowski, Alessia Le Donne, Pere Roca i Cabarrocas, Chrostowski, M, Alvarez, J, Le Donne, A, Binetti, S, i Cabarrocas, P, TOTAL S.A., TOTAL FINA ELF, Laboratoire de physique des interfaces et des couches minces [Palaiseau] (LPICM), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Institut Photovoltaïque d’Ile-de-France (ITE) (IPVF), Laboratoire Génie électrique et électronique de Paris (GeePs), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Milano-Bicocca Solar Energy Research Center (MIB-SOLAR), and Università degli Studi di Milano-Bicocca [Milano] (UNIMIB)
- Subjects
Photoluminescence ,Materials science ,Silicon ,Annealing (metallurgy) ,Silicon epitaxy ,PECVD ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Chemical vapor deposition ,B-H complexe ,01 natural sciences ,lcsh:Technology ,Article ,[SPI.MAT]Engineering Sciences [physics]/Materials ,Plasma-enhanced chemical vapor deposition ,Impurity ,b–h complexes ,0103 physical sciences ,General Materials Science ,Crystalline silicon ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,Boron ,lcsh:Microscopy ,lcsh:QC120-168.85 ,010302 applied physics ,lcsh:QH201-278.5 ,lcsh:T ,021001 nanoscience & nanotechnology ,CHIM/02 - CHIMICA FISICA ,chemistry ,B-H complexes ,lcsh:TA1-2040 ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,0210 nano-technology ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:TK1-9971 - Abstract
We investigate low-temperature (<, 200 °, C) plasma-enhanced chemical vapor deposition (PECVD) for the formation of p&ndash, n junctions. Compared to the standard diffusion or implantation processes, silicon growth at low temperature by PECVD ensures a lower thermal budget and a better control of the doping profile. We previously demonstrated the successful growth of boron-doped epitaxial silicon layers (p+ epi-Si) at 180 °, C. In this paper, we study the activation of boron during annealing via dark conductivity measurements of p+ epi-Si layers grown on silicon-on-insulator (SOI) substrates. Secondary Ion Mass Spectroscopy (SIMS) profiles of the samples, carried out to analyze the elemental composition of the p+ epi-Si layers, showed a high concentration of impurities. Finally, we have characterized the p+ epi-Si layers by low-temperature photoluminescence (PL). Results revealed the presence of a broad defect band around 0.9 eV. In addition, we observed an evolution of the PL spectrum of the sample annealed at 200 °, C, suggesting that additional defects might appear upon annealing.
- Published
- 2019
45. Integrins as biomechanical sensors of the microenvironment
- Author
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Johanna Ivaska, Pere Roca-Cusachs, and Jenny Z. Kechagia
- Subjects
Integrins ,Integrin ,Extracellular matrix ,Integrines ,03 medical and health sciences ,0302 clinical medicine ,Cell Movement ,Neoplasms ,Cell Adhesion ,Tumor Microenvironment ,Animals ,Humans ,Cell adhesion ,Molecular Biology ,030304 developmental biology ,0303 health sciences ,Tumor microenvironment ,biology ,Nanociència ,Chemistry ,Binding properties ,Cell Membrane ,Cell migration ,Cell Biology ,Matriu extracel·lular ,Cell function ,Cell biology ,Extracellular Matrix ,Neoplasm Proteins ,Nanoscience ,biology.protein ,030217 neurology & neurosurgery ,Function (biology) - Abstract
Integrins, and integrin-mediated adhesions, have long been recognized to provide the main molecular link attaching cells to the extracellular matrix (ECM) and to serve as bidirectional hubs transmitting signals between cells and their environment. Recent evidence has shown that their combined biochemical and mechanical properties also allow integrins to sense, respond to and interact with ECM of differing properties with exquisite specificity. Here, we review this work first by providing an overview of how integrin function is regulated from both a biochemical and a mechanical perspective, affecting integrin cell-surface availability, binding properties, activation or clustering. Then, we address how this biomechanical regulation allows integrins to respond to different ECM physicochemical properties and signals, such as rigidity, composition and spatial distribution. Finally, we discuss the importance of this sensing for major cell functions by taking cell migration and cancer as examples.
- Published
- 2019
46. Engineering island-chain silicon nanowires via a droplet mediated Plateau-Rayleigh transformation
- Author
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Mingkun Xu, Pere Roca i Cabarrocas, Jimmy Wang, Yaolong Zhao, Junzhuan Wang, Zhaoguo Xue, Jun Xu, Linwei Yu, Kunji Chen, Yi Shi, and Xiaofan Jiang
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inorganic chemicals ,Materials science ,Fabrication ,Science ,Nanowire ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,complex mixtures ,Article ,General Biochemistry, Genetics and Molecular Biology ,symbols.namesake ,0103 physical sciences ,Thin film ,Rayleigh scattering ,010306 general physics ,Nanoscopic scale ,Multidisciplinary ,business.industry ,technology, industry, and agriculture ,General Chemistry ,021001 nanoscience & nanotechnology ,Amorphous solid ,chemistry ,symbols ,Optoelectronics ,Photonics ,0210 nano-technology ,Tin ,business - Abstract
The ability to program highly modulated morphology upon silicon nanowires (SiNWs) has been fundamental to explore new phononic and electronic functionalities. We here exploit a nanoscale locomotion of metal droplets to demonstrate a large and readily controllable morphology engineering of crystalline SiNWs, from straight ones into continuous or discrete island-chains, at temperature, The ability to program periodic morphology into nanowires affords control over photonic and electronic transport properties. Here, the authors stimulate Plateau-Rayleigh transformations in silicon nanowires through an oscillating catalyst droplet, resulting in nanowires with island-chain morphology.
- Published
- 2016
47. Suppression of the thermal quenching of photoluminescence in irradiated silicon heterojunction solar cells
- Author
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Pere Roca i Cabarrocas, Alice Defresne, and Olivier Plantevin
- Subjects
Amorphous silicon ,Materials science ,Silicon ,chemistry.chemical_element ,02 engineering and technology ,01 natural sciences ,law.invention ,Monocrystalline silicon ,chemistry.chemical_compound ,law ,0103 physical sciences ,Solar cell ,Materials Chemistry ,Crystalline silicon ,Electrical and Electronic Engineering ,010302 applied physics ,business.industry ,Doping ,technology, industry, and agriculture ,Nanocrystalline silicon ,Heterojunction ,Surfaces and Interfaces ,equipment and supplies ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,eye diseases ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Optoelectronics ,sense organs ,0210 nano-technology ,business - Abstract
We report on the decrease in photoluminescence (PL) intensity with the increase of the sample temperature (thermal quenching) in crystalline silicon and its suppression after ion irradiation. The crystalline silicon surface was passivated with intrinsic and doped hydrogenated amorphous silicon (a-Si:H) layer stacks as for making silicon heterojunction solar cell precursors. Low energy argon ion irradiation, in the range between 5 and 17 keV, was used for controlled defect formation either in the thin a-Si:H top layer or at the interface with the crystalline silicon beneath. The irradiation defects introduce radiative recombination centers in the a-Si:H as can be measured from PL at low temperature. Moreover, the irradiation and annealing result in a strong modification of the thermal quenching of the PL intensity up to 500 K, showing evidence for the strong reduction of thermally activated non-radiative recombinations at the amorphous-crystalline interface. This result can have implications in the field of crystalline silicon surface passivation.
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- 2016
48. Analysis of p-type SiOxlayers as a boron diffusion source for n-type c-Si substrates
- Author
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Pere Roca i Cabarrocas, Julien Voillot, Prabal Goyal, E.V. Johnson, Elias Urrejola, and Junegie Hong
- Subjects
010302 applied physics ,Materials science ,Silicon ,Annealing (metallurgy) ,Analytical chemistry ,chemistry.chemical_element ,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 ,Secondary ion mass spectrometry ,chemistry ,Plasma-enhanced chemical vapor deposition ,0103 physical sciences ,Materials Chemistry ,Electrical and Electronic Engineering ,Thin film ,0210 nano-technology ,Boron ,Silicon oxide ,Sheet resistance - Abstract
We evaluate the use of p-type silicon oxide (p-SiOx) dielectric layers as a boron diffusion source for n-type crystalline silicon (c-Si) substrates. The p-SiOx layers grown on n-type c-Si substrates by plasma enhanced chemical vapor deposition using a gas mixture of He/hexamethyldisiloxane/CO2/B2H6 are thermally stable and do not peel off during annealing up to 1050 °C, making them effective diffusion sources. The layers were examined before and after annealing with characterization techniques including spectroscopic ellipsometry and secondary ion mass spectrometry. We observe that there is a reduction in the thickness of the p-SiOx layer after annealing by about 50%, and that boron diffuses into the n-type c-Si substrate, forming a p+ layer, limited by the formation of a carbon-rich layer above the c-Si surface. The concentration of holes in the diffused region was measured by the electrochemical capacitance–voltage technique, and it was found that essentially all the boron that diffused into the n-type c-Si was active, unaffected by the presence of carbon and oxygen atoms. The concentration of carriers can be controlled by the initial thickness of the p-SiOx layers and the depth of the p+/n junction can be controlled by the time of annealing. A surface carrier concentration of 3 × 1019 at cm−3 and a sheet resistance of the order of 120 Ω sq−1 was obtained upon annealing at 1050 °C for 30 min.
- Published
- 2016
49. Ultrathin PECVD epitaxial Si solar cells on glass via low-temperature transfer process
- Author
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Martin Foldyna, Anne Gaucher, Philippe Pareige, Inès Massiot, Jean-Luc Maurice, Andrea Cattoni, Pere Roca i Cabarrocas, Emmanuel Cadel, Valerie Depauw, Gilles Patriarche, Stéphane Collin, Ismael Cosme-Bolanos, Wanghua Chen, and Romain Cariou
- Subjects
Materials science ,Silicon ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,Chemical vapor deposition ,010402 general chemistry ,Epitaxy ,7. Clean energy ,01 natural sciences ,Monocrystalline silicon ,Photovoltaics ,Plasma-enhanced chemical vapor deposition ,Crystalline silicon ,Electrical and Electronic Engineering ,Renewable Energy, Sustainability and the Environment ,business.industry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,Anodic bonding ,Optoelectronics ,0210 nano-technology ,business - Abstract
Fabrication of high-quality ultrathin monocrystalline silicon layers and their transfer to low-cost substrates are key steps for flexible electronics and photovoltaics. In this work, we demonstrate a low-temperature and low-cost process for ultrathin silicon solar cells. By using standard plasma-enhanced chemical vapor deposition (PECVD), we grow high-quality epitaxial silicon layers (epi-PECVD) from SiH4/H2 gas mixtures at 175 °C. Using secondary ion mass spectrometry and transmission electron microscopy, we show that the porosity of the epi-PECVD/crystalline silicon interface can be tuned by controlling the hydrogen accumulation there. Moreover, we demonstrate that 13–14% porosity is a threshold above which the interface becomes fragile and can easily be cleaved. Taking advantage of the H-rich interface fragility, we demonstrate the transfer of large areas (∽10 cm2) ultrathin epi-PECVD layers (0.5–5.5 µm) onto glass substrates by anodic bonding and moderate annealing (275–350 °C). The structural properties of transferred layers are assessed, and the first PECVD epitaxial silicon solar cells transferred on glass are characterized. Copyright © 2016 John Wiley & Sons, Ltd.
- Published
- 2016
50. Interfacial hydrogen incorporation in epitaxial silicon for layer transfer
- Author
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Junyang An, Haeyeon Jun, Zhen Zheng, Wanghua Chen, Thi Bao Tran Nguyen, Ruiling Gong, Marta Chrostowki, Jean-Luc Maurice, 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), and ANR-10-EQPX-0050,TEMPOS,Microscopie electronique en transmission sur le plateau Palaiseau Orsay Saclay(2010)
- Subjects
Materials science ,Hydrogen ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,Substrate (electronics) ,010402 general chemistry ,Epitaxy ,01 natural sciences ,7. Clean energy ,Photovoltaics ,Crystalline silicon ,Porosity ,Layer transfer ,business.industry ,Surfaces and Interfaces ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Epitaxial Si ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry ,Anodic bonding ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Optoelectronics ,0210 nano-technology ,business ,Layer (electronics) - Abstract
International audience; Recently, epitaxial Si layers have attracted strong attention, particularly in photovoltaics. This successful application depends mainly on the easiness of their transfer to a foreign carrier substrate. Therefore, developing a simple and efficient method to realize the transfer is a key issue. A most delicate point is the lift-off of the epitaxial layer from its parent substrate. In this work, we present a method to weaken the interface based on hydrogen incorporation. We have been able to control the hydrogen content at the interface between the crystalline silicon substrate and the epitaxial films by changing the epitaxial growth conditions. Several bonding techniques have been tested and epitaxial Si films have been transferred successfully via anodic bonding. A hydrogen-assisted transferring mechanism is presented.
- Published
- 2020
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