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Nanostructuration d'objets métalliques sur surfaces à défauts

Abstract : This Ph-D concerns the theoretical study of self-organized growth of metallic or inert species adsorbed on stepped surfaces. The aim of this study was to provide a quantitative understanding of the microscopic mechanisms that are responsible for the formation of well-defined nanostructures near steps. In particular, we want to predict the best experimental conditions which lead to a given nanostructure characterized by its nature (wire, grating), its size and width. The growth of adsorbates on a surface has an out-of equilibrium behavior which is mainly describe by three processes such as deposition, diffusion and aggregation of adatoms on the surface. Therefore, this thesis has been splitted into three parts. The first part is a review of the different approches of the diffusion theory. This one allow us to justify the approximations that we have made when we have implemented the diffusion model into the growth code. The second part of the manuscript deals with the explanation of this Kinetic Monte-Carlo code and its limitations. Finally, the applications treated in my thesis are tackled in details. The main results that we have reached are: Occurence of a nanometer switch for xenon adsorbed on a two steps surface of Cu(110). Two different wires could be obtained near steps along the [100] and [1-10] directions of the copper surface. The step decoration is guided by the temperature and comes from the competition between the equilibrium and kinetic regimes. Confinement effects on the wire densities. The confinement effect, due to the finite size of the terraces between two steps strongly modify the auto-organized growth of metallic species on stepped surfaces. On small terraces like Pt(997), well-defined and dense wires of silver species are obtained. By contrast, on larger terraces, the islands attached to the steps exhibit a fractal shape without any periodic behavior. Formation of nanowires or nanogratings as a function of the confinement. On small terraces like Pt(997), a perfect grating formed by well-defined wires of silver species localized at step foot is obtained. For intermediate confinements, each step is decorated by a periodic arrangement of islands constituting a kind of grating. The associated wave-length can be controled by the temperature and coverage rate of adsorbate deposited on the surface. This work is not ended at all and opens the way to different possible investigations. For instance, the formation of metallic alloys formed in out-of equilibrium is probably very promising for the information storage. KEYWORDS Growth Diffusion Semi-empirical potentials Kinetic Monte Carlo Confinement Nanostructure and nanowire
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https://tel.archives-ouvertes.fr/tel-00002670
Contributor : Fabien Picaud <>
Submitted on : Wednesday, April 2, 2003 - 10:18:19 AM
Last modification on : Tuesday, October 27, 2020 - 2:34:47 PM
Long-term archiving on: : Tuesday, September 11, 2012 - 8:10:32 PM

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  • HAL Id : tel-00002670, version 1

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Fabien Picaud. Nanostructuration d'objets métalliques sur surfaces à défauts. Modélisation et simulation. Université de Franche-Comté, 2001. Français. ⟨tel-00002670⟩

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