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Portavoce A.,CNRS Institute Materials Microelectronics nanosciences of Provence | Treglia G.,French National Center for Scientific Research
Acta Materialia | Year: 2014

The distribution of fast-diffusing interstitial impurities (Ni, Cu, etc.) in the vicinity of a dislocation loop in Si bulk is theoretically investigated, at the atomic scale, using the Si Stillinger-Weber potential via Monte Carlo and kinetic Monte Carlo simulations. The Si dislocation loop is modeled by an extra Si plane introduced between two Si(1 1 1) planes. Interstitial impurities are shown to gather on the dislocation loop edges only, in interstitial sites of minimum pressure. These results are in agreement with experimental atom probe tomography observations related to Ni accumulation on Si dislocation loops, and can be interpreted as a Cottrell atmosphere. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Merlen A.,CNRS Institute Materials Microelectronics nanosciences of Provence | Lagugne-Labarthet F.,University of Western Ontario
Applied Spectroscopy | Year: 2014

Over the past five years, new developments in the field of plasmonics have emerged with the goal of finely tuning a variety of metallic nanostructures to enable a desired function. The use of plasmonics in spectroscopy is of course of great interest, due to large local enhancements in the optical near field confined in the vicinity of a metal nanostructure. For a given metal, such enhancements are dependent on the shape of the structure as well as the optical properties (wavelength, phase, polarization) of the impinging light, offering a large degree of control over the optical and spatial localization of the plasmon resonance. In this focal point, we highlight recent work that aims at revealing the spatial position of the localized plasmon resonances using a variety of optical and non-optical methods. © 2014 Society for Applied Spectroscopy.

Saul A.,CNRS Interdisciplinary Nanoscience Centre of Marseille | Radtke G.,CNRS Institute Materials Microelectronics nanosciences of Provence
Physical Review Letters | Year: 2011

Concerning its magnetic properties, the layered vanadate CsV 2O5 has long been considered as formed by isolated spin-1/2 dimers characterized by a large antiferromagnetic coupling of about 146K. This interpretation was supported by both magnetic susceptibility measurements and the obvious presence of magnetically active strongly dimerized V4+ ions. In this work we investigate the magnetic properties of this compound through an extensive use of the broken-symmetry formalism in the framework of density-functional theory. Our calculations demonstrate that the system is built from strongly dimerized alternating chains where the structural and magnetic dimers are distinct from each other. © 2011 American Physical Society.

Portavoce A.,CNRS Institute Materials Microelectronics nanosciences of Provence
Scripta Materialia | Year: 2015

B concentration profiles measured by secondary ion mass spectrometry in a 250 nm thick nanocrystalline Si (nc-Si) layer made of 50 nm wide grains show unusual diffusion profiles. The usual B diffusion model, which takes into account the variation of the B lattice diffusion coefficient with B concentration, fails to explain the profiles measured in nc-Si. In contrast, B diffusion profiles can be well fitted using a model that takes into account moving grain boundaries with a B-concentration-dependent migration rate. © 2014 Acta Materialia Inc. All rights reserved.

Gaillard P.,CNRS Institute Materials Microelectronics nanosciences of Provence | Aqua J.-N.,University Pierre and Marie Curie | Frisch T.,CNRS Non-Linear Institute of Nice
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We investigate the nucleation and growth of anisotropic and strained quantum dots in heteroepitaxy by means of kinetic Monte Carlo simulations. Surface energy anisotropy is introduced in order to depict Ge-like dots with (105) facets growing on a Si (100) substrate. Three dimensional islands, mainly in the form of square-base pyramids, are reported and their coarsening is found to be interrupted during annealing. The resulting island density follows the scaling law ρ∼(D/F)-α with αâ‰0.6 as a function of the diffusion D to flux F ratio. The island size distribution follows the scaling law resulting from the assumption of a single length scale. © 2013 American Physical Society.

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