Quantum calculations of the carrier mobility in thin films: Methodology, Matthiessen's rule and comparison with semi-classical approaches

We discuss the calculation of the carrier mobility in silicon films within the quantum Non-Equilibrium Green's Functions (NEGF) framework. We introduce a new method for the extraction of the carrier mobility that is free from contact resistance contamination, and provides accurate mobilities at a reasonable cost, with minimal needs for ensemble averages. We then introduce a new paradigm for the definition of the partial mobility $\mu_{M}$ associated with a given elastic scattering mechanism "M", taking phonons (PH) as a reference ($\mu_{M}^{-1}=\mu_{PH+M}^{-1}-\mu_{PH}^{-1}$). We argue that this definition makes better sense in a quantum transport framework as it is free from long range interference effects that can appear in purely ballistic calculations. As a matter of fact, these mobilities satisfy Matthiessen's rule for three mechanisms [surface roughness (SR), remote Coulomb scattering (RCS) and phonons] much better than the usual, single mechanism calculations. We also discuss the problems raised by the long range spatial correlations in the RCS disorder. Finally, we compare semi-classical Kubo-Greenwood (KG) and quantum NEGF calculations. We show that KG and NEGF are in reasonable agreement for phonon and RCS, yet not for SR. We point to possible deficiencies in the treatment of SR scattering in KG, opening the way for further improvements.Comment: Submitted to Journal of Applied Physic

フランスラグビーのプロ化過程と三つの主要エージェント

This article is the synthesis of a common thought with Pascal CHANTELAT and Pierre CHAIX. It presents the four great stages of the process of professionalization of French Rugby. It more particularly exposes how the managers of French Rugby face the advance of the process of professionalism initiated since the end of 1980. The arrival of new actors, in particular the National professional League of Rugby (LNR) and the Trade union of players (PROVALE), has shown the end of monopoly of the French Federation (FFR) in the management and organization of this sport. During the years 1987-2004. the changes in the definition of the rules of the game to the sporting direction (methods of organization of games) and socio-politic direction (the collective distribution of power and money), was marked by a series of hesitations and inversions of orientation, This indecision mainly arose from confrontation between the union on one side and the professional league on the other. These two organizations were mainly represented by the Presidents of the professional clubs. These entities were in conflict for controlling the "Rugby Spectacle". The analysis of the projects (talks and documents from the clubs or the union) and of the strategies from the various entities shows that this style of management reveals more about the amount of influence and opportunist strategies of alliance than that of a true governorship based on a common vision of professional Rugby, with forms of cooperation between all entities

Effective field and universal mobility in high-k metal gate UTBB-FDSOI devices

session 1: parameter extractionInternational audienceThis paper aims at reviewing experimental and theoretical behaviors of universal mobility in high-k metal gate UTBB-FDSOI devices. Based on split-CV mobility measurements, the parameter η, characterizing the effective field, has been extracted for a large range of back voltages and temperatures in devices with various equivalent oxide thicknesses. We demonstrated that a nearly universal trend for the mobility with respect to the effective field can be obtained in the front inversion regime but is difficult to obtain in the back channel inversion regime. Keywords—FDSOI, universal mobility, effective field, coefficient η

Stratégies de professionnalisation de cinq clubs de rugby de l’élite Européenne

Cet article est issu d’un travail de thèse intitulé Professionnalisation du rugby et stratégies de clubs de l’élite Européenne. Partant du constat que les clubs de rugby sont de plus en plus soumis à une logique économique, particulièrement ceux qui pratiquent à haut niveau, l’objectif de cette recherche est d’étudier les effets du processus de « professionnalisation » au sein des clubs de rugby de l’élite européenne. Ainsi, après avoir défini le rugby comme un « système » c’est-à-dire comme ..

Développement de la modélisation TCAD pour l'ingénierie de la contrainte dans les dispositifs CMOS avancés sur film minces

The design of nanoscale CMOS devices brings new challenges to TCAD community. Indeed, nowadays, CMOS performances improvements are not simply due to device scaling but also to the introduction of new technology “boosters” such as new transistors architectures (FDSOI, trigate), high-k dielectric gate stacks, stress engineering or new channel material (Ge, III-V). To face all these new technological challenges, Technology Computer Aided Design (TCAD) is a powerful tool to guide the development of advanced technologies but also to reduce development time and cost. In this context, this PhD work aimed at improving the modeling for 28/14 and 10FDSOI technologies, with a particular attention on mechanical strain impacts. In the first section, a summary of the main models implemented in state of the art device simulators is performed. The limitations and assumptions of these models are highlighted and developments of the in-house STMicroelectronics KG solvers are discussed. In the second section, a “top down” approach has been set-up. It has consisted in using advanced physical-based solvers as a reference for TCAD empirical models calibration. Calibrated TCAD reproduced accurately split-CV mobility measurements varying the temperature, the back bias and the Interfacial Layer (IL) thickness. The third section deals with a description of the methodologies used during this thesis to model stress induced by the process flow. Simulations are compared to nanobeam diffraction (NBD) strain measurements. The use and calibration of available TCAD models to efficiently model the impact of stress on mobility in a large range of stress (up to 2GPa) is also discussed in this section. The last part deals with TCAD modeling of advanced CMOS devices for 28/14 and 10FDSOI technology development. Mechanical simulations are performed to model the stress profile in transistors and several solutions to optimize the stress configuration in sSOI and SiGe-based devices have been presented.La conception des dispositifs nanométriques CMOS apporte de nouveaux défis à la communauté TCAD. En effet, de nos jours, les améliorations des performances des transistors ne sont plus simplement dû à une simple diminution des dimensions des dispositifs, mais aussi à l'introduction de boosters de technologies tels que des nouvelles architectures (FDSOI, trigate), des oxydes de grille à forte permittivité, l'ingénierie de la contrainte ou de nouveaux matériaux de canal (Ge, III-V). Pour faire face à tous ces nouveaux défis technologiques, la modélisation TCAD (Technology Computer Aided Design) est un outil puissant pour guider le développement mais aussi pour réduire les coûts. Dans ce contexte, ce travail de thèse vise à améliorer la modélisation TCAD pour les technologies 28/14 et 10FDSOI, avec une attention particulière sur les impacts des contraintes mécaniques sur leurs performances. Dans un premier temps, les différents mécanismes impactant la mobilité des technologies FDSOI ont été étudiés en détail. Les modèles implémentés dans des outils de simulations avancés (NEGF, Multi subbands Monte Carlo, Kubo-Greenwood) sont étudiés, comparés et des développements du logiciel interne à STMicroelectronics (UTOXPP) sont proposés. Dans un second temps, une approche « top down » a été mis en place. Elle consiste à calibrer les modèles TCAD empiriques non pas sur des mesures mais sur des outils de simulations avancés (Kubo-Greenwood). Les modèles TCAD calibrés montrent de très bons accords avec les mesures de mobilité (split-CV) en variant la température, la polarisation du substrat et l’épaisseur de l’IL (Interfacial layer). Dans un troisième temps, les méthodes utilisées lors de cette thèse pour modéliser les contraintes induites par le procédé de fabrications sont décrites. Enfin, la dernière partie concerne la modélisation TCAD des technologies 28 et 14FDSOI. Des simulations mécaniques sont effectuées pour modéliser les profils de contraintes dans les transistors. Des solutions pour optimiser la configuration des contraintes dans le canal pour ces technologies sont proposées

Formation innovante des arbitres féminins de la F.F. Voile

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Formation innovante des arbitres féminins de la F.F. Voile

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Le marché des biens sportifs d'occasion: consommation postmoderne ou rationalisation?

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