Utilisation des gels ioniques pour l'étude de nanostructures semi-conductrices

Utilisation des gels ioniques pour l'étude de nanostructures semi-conductrices PDF Author: Francis Quenneville
Publisher:
ISBN:
Category :
Languages : fr
Pages : 117

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Utilisation des gels ioniques pour l'étude de nanostructures semi-conductrices

Utilisation des gels ioniques pour l'étude de nanostructures semi-conductrices PDF Author: Francis Quenneville
Publisher:
ISBN:
Category :
Languages : fr
Pages : 117

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Élaboration et caractérisation de films vitreux nanostructurés par voie sol-gel

Élaboration et caractérisation de films vitreux nanostructurés par voie sol-gel PDF Author: Gilles Ehrhart
Publisher:
ISBN:
Category :
Languages : fr
Pages : 181

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Ce travail concerne l'élaboration et la caractérisation de guides d'onde planaires non dopés et dopés par des nanoparticules semi-conductrices et/ou des ions de terre rare. Ce type de dispositif trouve son intérêt dans l'étude de nouveaux systèmes dans le cadre des Technologies Avancées pour les Télécommunications Optiques. Il est bien connu que les systèmes optiques nécessite l'emploi d'amplificateurs afin de compenser les pertes optiques dans les circuits. Ces amplificateurs pourraient avoir un meilleur rendement et une plus grande souplesse grâce au transfert d'énergie entre nanoparticules semi-conductrices et ions de terre rare. En effet, les nanoparticules de semi-conducteur présentent d'une part des sections efficaces d'absorption plus importantes, de plusieurs ordres de grandeur que celles des ions de terre rare, et d'autre part des bandes d'absorption plus larges permettant l'accordabilité du pompage et l'augmentation du rendement optique. Afin d'étudier le phénomène de transfert d'énergie entre les nanoparticules de semiconducteur et les ions de terre rare, nous avons préparé des guides d'onde à base de ZrO2, non dopés et dopés, par le procédé sol-gel. Leurs propriétés optogéométriques ont été déterminées en utilisant la spectroscopie «m-lines» et en mesurant leurs coefficients d'atténuation. La spectroscopie Raman en configuration guidée a été utilisée pour caractériser la structure de ces guides et pour étudier les mécanismes accompagnant leur densification. Cette étude a été complétée par le biais de différentes techniques expérimentales telle que la spectroscopie d'émission utilisant l'ion Eu3+ comme sonde structurale. La mise en évidence de l'Influence du dopage par les ions Eu3+ se traduit par un ralentissement du processus de densification du réseau de zircone. Un autre dopage a ensuite été opéré à l'aide de nanoparticules de CdS et de ZnS. Les précurseurs des métaux et du soufre ont été introduits directement dans le sol de ZrO2 amenant à la précipitation in situ des particules lors du recuit. Leur taille et leurs propriétés d'émission ont été étudiées par les spectroscopies d'absorption UV-visible, d'émission et d'excitation. Enfin, le transfert d'énergie a été caractérisé lors du co-dopage de ZrO2 par ZnS:Eu3+. La spectroscopie d'émIssion de l'ion Eu3+ par excitation dans l'UV nous a montré une exaltation de rémission d'un facteur 42 à 10 K. La spectroscopie d'excitation de l'ion Eu3+ a confirmé l'existence du transfert d'énergie par l'émergence d'une bande liée à l'absorption des particules.

Graphene

Graphene PDF Author: Wonbong Choi
Publisher: CRC Press
ISBN: 1439861889
Category : Science
Languages : en
Pages : 374

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Book Description
Since the late 20th century, graphene-a one-atom-thick planar sheet of sp2-bonded carbon atoms densely packed in a honeycomb crystal lattice-has garnered appreciable attention as a potential next-generation electronic material due to its exceptional properties. These properties include high current density, ballistic transport, chemical inertness,

ICREEC 2019

ICREEC 2019 PDF Author: Ahmed Belasri
Publisher: Springer Nature
ISBN: 9811554447
Category : Technology & Engineering
Languages : en
Pages : 659

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Book Description
This book highlights peer reviewed articles from the 1st International Conference on Renewable Energy and Energy Conversion, ICREEC 2019, held at Oran in Algeria. It presents recent advances, brings together researchers and professionals in the area and presents a platform to exchange ideas and establish opportunities for a sustainable future. Topics covered in this proceedings, but not limited to, are photovoltaic systems, bioenergy, laser and plasma technology, fluid and flow for energy, software for energy and impact of energy on the environment.

Organic Solid-State Lasers

Organic Solid-State Lasers PDF Author: Sébastien Forget
Publisher: Springer
ISBN: 3642367054
Category : Science
Languages : en
Pages : 179

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Book Description
Organic lasers are broadly tunable coherent sources, potentially compact, convenient and manufactured at low-costs. Appeared in the mid 60’s as solid-state alternatives for liquid dye lasers, they recently gained a new dimension after the demonstration of organic semiconductor lasers in the 90's. More recently, new perspectives appeared at the nanoscale, with organic polariton and surface plasmon lasers. After a brief reminder to laser physics, a first chapter exposes what makes organic solid-state organic lasers specific. The laser architectures used in organic lasers are then reviewed, with a state-of-the-art review of the performances of devices with regard to output power, threshold, lifetime, beam quality etc. A survey of the recent trends in the field is given, highlighting the latest developments with a special focus on the challenges remaining for achieving direct electrical pumping of organic semiconductor lasers. A last chapter covers the applications of organic solid-state lasers.

ZnO Thin Films

ZnO Thin Films PDF Author: Paolo Mele
Publisher:
ISBN: 9781536160864
Category : Zinc oxide thin films
Languages : en
Pages : 0

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Book Description
Zinc oxide (ZnO) is an n-type semiconductor with versatile applications such as optical devices in ultraviolet region, piezoelectric transducers, transparent electrode for solar cells and gas sensors. This book "ZnO Thin Films: Properties, Performance and Applications" gives a deep insight in the intriguing science of zinc oxide thin films. It is devoted to cover the most recent advances and reviews the state of the art of ZnO thin films applications involving energy harvesting, microelectronics, magnetic devices, photocatalysis, photovoltaics, optics, thermoelectricity, piezoelectricity, electrochemistry, temperature sensing. It serves as a fundamental information source on the techniques and methodologies involved in zinc oxide thin films growth, characterization, post-deposition plasma treatments and device processing. This book will be invaluable to the experts to consolidate their knowledge and provide insight and inspiration to beginners wishing to learn about zinc oxide thin films.

Flexoelectricity in Liquid Crystals

Flexoelectricity in Liquid Crystals PDF Author: Agnes Buka
Publisher: World Scientific
ISBN: 1848167997
Category : Science
Languages : en
Pages : 299

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Book Description
The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.

Modern Surface Organometallic Chemistry

Modern Surface Organometallic Chemistry PDF Author: Jean-Marie Basset
Publisher: John Wiley & Sons
ISBN: 3527627103
Category : Science
Languages : en
Pages : 725

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Book Description
Covering everything from the basics to recent applications, this monograph represents an advanced overview of the field. Edited by internationally acclaimed experts respected throughout the community, the book is clearly divided into sections on fundamental and applied surface organometallic chemistry. Backed by numerous examples from the recent literature, this is a key reference for all chemists.

X-Ray and Neutron Reflectivity: Principles and Applications

X-Ray and Neutron Reflectivity: Principles and Applications PDF Author: Jean Daillant
Publisher: Springer Science & Business Media
ISBN: 3540486968
Category : Science
Languages : en
Pages : 347

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Book Description
The reflection of and neutrons from surfaces has existed as an x-rays exp- imental for almost it is in the last technique fifty Nevertheless, only years. decade that these methods have become as of enormously popular probes This the surfaces and interfaces. to be due to of several appears convergence of intense different circumstances. These include the more n- availability be measured orders tron and sources that can over (so reflectivity x-ray many of and the much weaker surface diffuse can now also be magnitude scattering of thin films and studied in some the detail); growing importance multil- basic the realization of the ers in both and technology research; important which in the of surfaces and and role roughness plays properties interfaces; the of statistical models to characterize the of finally development topology its and its characterization from on roughness, dependence growth processes The of and to surface scattering experiments. ability x-rays neutro4s study four five orders of in scale of surfaces over to magnitude length regardless their and also their to ability probe environment, temperature, pressure, etc. , makes these the choice for buried interfaces often probes preferred obtaining information about the microstructure of often in statistical a global surfaces, the local This is manner to complementary imaging microscopy techniques, of such studies in the literature witnessed the veritable by explosion published the last few Thus these lectures will useful for over a resource years.

Encyclopedia of Surface and Colloid Science

Encyclopedia of Surface and Colloid Science PDF Author: P. Somasundaran
Publisher: CRC Press
ISBN: 9780849395741
Category : Science
Languages : en
Pages : 1084

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Book Description