336 research outputs found
Low temperature raised source and drain epitaxy for Fully Depleted Silicon on Insulator (FD-SOI) technology
No full textCe travail de thèse s’inscrit dans la technologie de fabrication de transistors à canal mince (Si ou SiGe) totalement déserté sur isolant (Fully-Depleted Silicon-on-Insulator ou FDSOI) qui constitue une option prometteuse pour les nœuds 14nm et au-delà. Les problèmes liés à cette nouvelle technologie sont dus à : (1) l’existence d’instabilités morphologiques conduisant, lors de recuits haute température, à la fragmentation de la couche mince formant le canal, (2) la nécessité d’une reprise d’épitaxie SiGe:B afin de former, sur le canal, des sources et drains surélevées (Raised Source and Drain ou RSD) et (3) des problèmes liés à l’hétérogénéité du dopage induits par l’importance des interfaces substrat/canal, canal/Source et canal/Drain.Ce travail expérimental a été effectué au sein de la société STMicroelectronics en partenariat avec le Centre Interdisciplinaire de Nanoscience de Marseille. Les principaux résultats obtenus sont : 1/ La mise au point, puis l’optimisation d’une méthode de nettoyage de surface à basse température permettant d’éviter la fragmentation du canal observée lors de recuits haute température.2/ L’optimisation des conditions de préparation de la surface du canal permettant de réaliser une bonne reprise d’épitaxie pour les sources et drains surélevées.3/ L’optimisation, via l’incorporation de carbone, des profils de dopage au bore des sources et drains épitaxiés. Les tests électriques effectués sur dispositifs industriels montrent que, grâce aux développements réalisés au cours de ces travaux de thèse, le pourcentage de puces actives sur une plaque est passé de 40% à 90%.This work concerns the Fully-Depleted Silicon-On-Insulator (FD-SOI) technology, which is a promising option for the technical nodes beyond 14nm.The use of a very thin Si or SiGe channel causes new technological problems due to (1) morphological instabilities that break the film during its high temperature annealing, (2) the necessity to grow Raised Source & Drain (RSD) by epitaxial Chemical-Vapor Deposition (CVD) of SiGe:B, (3) the non-uniformity of the boron profile in the channel because of the number of interfaces (substrate/channel, channel/ source, channel/drain). This experimental work has been performed at STMicroelectronics and Nanoscience Interdisciplinary Center of Marseille laboratory. The main results are:1/ The definition and the improvement of an efficient low temperature surface-cleaning process that avoids the dewetting of the channel.2/ The optimization of the surface preparation of the channel for a subsequent epitaxial growth of RSD materials compatible with electronic requirements.3/ The improvement, via carbon incorporation, of the boron dopant profile in the epitaxially grown RSD. Analysis of electrical devices show that all these improvements lead to a huge enhancement of the percentage of electrical active dies per wafer (from 40% to 90 %)
Growth and ferroelectricity of GeTe on Si(111)
No full textL’effet Rashba géant mesuré récemment dans GeTe a montré le potentiel pour la spintronique des matériaux ferroélectriques avec un fort couplage spin-orbite. Dans cette thèse nous avons réalisé la croissance de films minces de GeTe sur Si(111)-Sb par épitaxie par jet moléculaire dans une large gamme d’épaisseur. À 270°C, nous observons une croissance couche-par-couche et une relation d’épitaxie principale GeTe(111) ∥Si(111) et GeTe[110] ∥Si[110]. En outre des nanodomaines ferroélastiques apparaissent dont la fraction volumique ainsi que la taille peuvent être contrôlées en ajustant finement l’épaisseur et la température de dépôt. Leur maille est identique à celle du domaine principal (rhomboédrique avec ar = 0.429 nm et θ = 58.3°). L’axe [111] de leur maille et leur polarisation électrique sont inclinés d’environ 72° par rapport à l’axe [111] du domaine principal. Nous mettons en évidence par microscopie à effet tunnel à la surface des domaines ferroélastiques trois structures surfaciques différentes, En analysant de façon détaillée l’interface GeTe/Si par microscopie électronique en transmission, nous démontrons que les dislocations de désaccord paramétrique localisées à l’interface formées pendant la croissance jouent un rôle clé dans la stabilité des nanodomaines ferroélectriques. Finalement, nous avons caractérisé la structure de bande électronique des domaines majoritaires de GeTe et mesuré une constante Rashba αr = 0.49 eV.nm qui diminue avec l’épaisseur des couches minces. De premières mesures par spectroscopie d’émission de photo-électrons résolues angulairement en dichroïsme circulaire ont permis de caractériser la courbure de Berry des films minces de GeTe.The recently measured giant Rashba effect in GeTe has shown the potential for spintronics of ferroelectric materials with large spin-orbit coupling. In this thesis we have grown GeTe thin films on Si(111)-Sb by molecular beam epitaxy in a wide range of thickness. At 270°C, we observe a layer-by-layer growth and a main epitaxial relationship GeTe(111) ∥Si(111) and GeTe[110] ∥Si[110]. In addition, ferroelastic nanodomains appear which volume fraction and size can be controlled by fine tuning the thickness and the deposition temperature. Their unit cell is identical to that of the main domain (rhombohedral with ar = 0.429 nm and θ = 58.3°). The [111] axis of their unit cell and their electrical polarization are tilted by about 72° with respect to the [111] axis of the main domain. We show by scanning tunneling microscopy that the surface of the ferroelastic nanodomains have three different surface structures. By a detailed analysis of the GeTe/Si interface by transmission electron microscopy, we demonstrate that misfit dislocations localized at the interface formed during growth play a key role in the stability of ferroelectric nanodomains. Finally, we have characterized the electronic band structure of the GeTe majority domains and measured a Rashba constant αr = 0.49 eV.nm that decreases with film thickness. First measurements to characterize the Berry curvature are performed by circular dichroism in angle-resolved photoemission spectroscopy
Nanostructures auto-assemblées : des systèmes modèles pour le micromagnétisme de parois magnétiques
No full textThe aim of this work is to control, using an external magnetic field, the internal structure of a magnetic domain wall. We chose to work on the asymmetric Bloch wall that has been studied in a model system : epitaxial self-assembled Fe(110) dots. We have evidenced the reversal of an internal degree of freedom of the domain wall : the orientation of the Néel caps that terminate the domain wall at both surfaces. This has been observedstatistically at remanence after applying an external magnetic field using XMCD-PEEM magneticmicroscopy, in quantitative agreement with micromagnetic simulations. Preliminary results of the direct observation of this phenomenon have been obtained using Lorentz microscopy. A magneto-transport study has been conducted on individual dots as a function of temperature. To do so, a procedure based on electronic lithography technique to contact individual dots has been developed. On the same experimental system, we have carried outa complementary study of the transition between a domain wall (2D) and a magnetic vortex (1D) that has been shown to be of second order kind. The transition and stochastic fluctuations between a domain wall and a vortex have been evidenced using Lorentz microscopy.L'objectif de cette thèse est le contrôle, par un champ magnétique, de la structure interne d'une paroi de domaines. Nous avons sélectionné le cas d'une paroi deBloch asymétrique, que nous avons étudié dans un système modèle : des plots épitaxiés autoassemblés de Fe(110). Nous avons mis en évidence la possibilité de procéder au retournement accompagné d'un phénomène d'hystérésis magnétique d'un des degrés de liberté internes, le sens des domaines de fermeture de Néel qui terminent la paroi à chaque surface. Ceci a été observé à rémanence après aimantation et de manière statistique par microscopie magnétique XMCD-PEEM, en accord quantitatif avec des simulations micromagnétiques. Des résultats préliminaires de la mise en évidence directe sous champ magnétique ont été obtenus par microscopie de Lorentz. Une étude sous champ et en température a été menée par magnéto-transport sur des plots individuels. Pour ce faire, un procédé de contactage de plots individuels par lithographie électronique a été développé. En complément mais sur le même système expérimental, nous avons étudié comment s'opère la transition entre une paroi magnétique (2D) et un vortex magnétique (0D), que nous avons montré être de second ordre. La transition et les fluctuations stochastiques entre une paroi et un vortex ont été mises en évidence par microscopie de Lorentz
particleShear: Discrete Python particle simulation with digital rheology and stress tensor evaluation
No full textparticleShear: Python package for particle shear simulation
This package provides a discrete particle simulation kit for having multiple spheres interacting. The spheres (i.e. 2D circles) interact by mutual elastic repulsion and tangential friction upon contact, but can also be crosslinked together. In addition to the elementary implementation of the interacting particles, it is also possible to define rheological experiments where the spheres are exposed to sinusoidally varying displacement conditions on the boundaries. We paid particular attention to avoid pitfalls that generate asymmetric stress tensors.
Acknowledgement: Thanks from the author go to Fabien Bonini and Joé Brefie-Guth for package testing, and to Daniel Lyobenov for initial help with simulation setup.
This repository archives the releases of the source code hosted at https://github.com/tbgitoo/particleShear. The package is available through the Python package server (see https://pypi.org/project/particleShear/1.0.2/). It can be installed automatically in python via
pip3 install particleShear
In some installations, the command may also be pip install particleShear; the minimal version of Python is 3.
Optimizing construction of scheduled data flow graph for on-line testability
No full textThe objective of this work is to develop a new methodology for behavioural synthesis using a flow of synthesis, better suited to the scheduling of independent calculations and non-concurrent online testing. The traditional behavioural synthesis process can be defined as the compilation of an algorithmic specification into an architecture composed of a data path and a controller. This stream of synthesis generally involves scheduling, resource allocation, generation of the data path and controller synthesis. Experiments showed that optimization started at the high level synthesis improves the performance of the result, yet the current tools do not offer synthesis optimizations that from the RTL level. This justifies the development of an optimization methodology which takes effect from the behavioural specification and accompanying the synthesis process in its various stages. In this paper we propose the use of algebraic properties (commutativity, associativity and distributivity) to transform readable mathematical formulas of algorithmic specifications into mathematical formulas evaluated efficiently. This will effectively reduce the execution time of scheduling calculations and increase the possibilities of testability
Dataset: Stability of hemicarbonate under cement paste-like conditions
No full textData, and scripts (analysis, plots) to go with the publication:
Stability of hemicarbonate under cement paste-like conditions
Fabien Georget (a,1,∗), Barbara Lothenbach (b) , William Wilson (a,c) , Franco Zunino (a) Karen L. Scrivener (a)
a: aboratory of Construction Materials, LMC, EPFL-STI-IMX, Station 12, CH-1015
Lausanne, Switzerland
b: Empa, Concrete & Asphalt Laboratory, Dübendorf, Switzerland
c: Sherbrooke University, Sherbrooke, Quebec, Canada
1: current address: Institute of Building Materials Research, RWTH Aachen, Aachen, Germany
* corresponding author
To be submitted to Cement and Concrete Researc
Author Correction: A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids
No full textVagabondage dans Le Mont Damion d’André Dhôtel
No full textThe paper discusses the theme of wandering in the novel by French author André Dhôtel. The protagonist of Le Mont Damion, Fabien Gort, is not a typical vagrant, as he is a member of an intellectual and quite rich family. However, because of his strong absent-mindedness and strangeness, Fabien is unable to find a place in social structures. People’s hostility leads him to many wanderings and unexpected encounters which influence his existence. The novel seems to be also a generic wandering, as it possesses some features of picaresque novel, adventure novel, initiation story and fairytale fantasy
Surface-dependent scenarios for dissolution-driven motion of growing droplets
No full textInternational audienceNano-droplets on a foreign substrate have received increasing attention because of their technological possible applications, for instance to catalyse the growth of nanowires. In some cases the droplets can move as a result of a reaction with the substrate. In this work we show that the substrate orientation, the surface morphology and the shape of the pits etched in the substrate by the droplets affect the droplet motion, so that a single mechanism (droplet-induced substrate dissolution) may lead to several unexpected droplet dynamics. The experiments are carried out by low energy electron microscopy on Au-Si and Au-Ge, which are model systems for studying liquid droplet alloys. Studying in-situ the behaviour of Au droplets on various Si and Ge surfaces, we describe a subtle interplay between the substrate orientation, the surface defects, and the droplet motion. Our observations allow a deep understanding of the interfacial mechanisms at the origin of the alloy formation and the associated droplet motion. These mechanisms are based on events of substrate dissolution/recrystallization. The outcomes of this work highlight the importance of the etching anisotropy on the droplet-substrate behaviours, and are essential in the perspective of positioning liquid alloy droplets used for instance as nanowire catalysts
Early-life and chronic exposure to high-fat diet alters noradrenergic and glutamatergic neurotransmission in the male rat amygdala and hippocampus under cognitive challenges
No full textOBEETEEN Consortium: Guillaume Ferreira, Gustavo Pacheco-Lopez, Etienne Coutureau, Ranier Gutierrez, Pascal Barat, Federico Bermudez-Rattoni, Gwenaelle Catheline, Claudia I. Pérez,, Pauline Lafenêtre, Daniel Osorio-Gomez, Kioko Guzman-Ramos, Fabien Naneix, Ernesto Sanz-Arigita, Ioannis Bakoyiannis. Note: Consortium author list recognizes the significant and irreducible commitment with the conceptualization, management, and realization of this research project.Peer reviewe
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