Swift Highly Charged Ion Channelling

We review recent experimental and theoretical progress made in the scope of swift highly charged ion channelling in crystals. The usefulness of such studies is their ability to yield impact parameter information on charge transfer processes, and also on some time related problems. We discuss the cooling and heating phenomena at MeV/u energies, results obtained with decelerated H-like ion beams at GSI and with ions having an excess of electrons at GANIL, the superdensity effect along atomic strings and Resonant Coherent Excitation.Comment: to be published in Journal of Physics

Multicharacterization approach for studying InAl(Ga)N/Al(Ga)N/GaN heterostructures for high electron mobility transistors

We report on our multi–pronged approach to understand the structural and electrical properties of an InAl(Ga)N(33nm barrier)/Al(Ga)N(1nm interlayer)/GaN(3μm)/AlN(100nm)/Al2O3 high electron mobility transistor (HEMT) heterostructure grown by metal organic vapor phase epitaxy (MOVPE). In particular we reveal and discuss the role of unintentional Ga incorporation in the barrier and also in the interlayer. The observation of unintentional Ga incorporation by using energy dispersive X–ray spectroscopy analysis in a scanning transmission electron microscope is supported with results obtained for samples with a range of AlN interlayer thicknesses grown under both the showerhead as well as the horizontal type MOVPE reactors. Poisson–Schrödinger simulations show that for high Ga incorporation in the Al(Ga)N interlayer, an additional triangular well with very small depth may be exhibited in parallel to the main 2–DEG channel. The presence of this additional channel may cause parasitic conduction and severe issues in device characteristics and processing. Producing a HEMT structure with InAlGaN as the barrier and AlGaN as the interlayer with appropriate alloy composition may be a possible route to optimization, as it might be difficult to avoid Ga incorporation while continuously depositing the layers using the MOVPE growth method. Our present work shows the necessity of a multicharacterization approach to correlate structural and electrical properties to understand device structures and their performance

Manpower development for the Water Decade in SE Asia

Manpower development for the Water Decade in SE Asi

Handbook Handbook on Best Practice for Minimising Beam Induced Damage during IBA SPIRIT

This handook is intended as a resource for scientists who use Ion Beam Analysis (IBA), to help them understand and minimise beam damage induced during the analysis. The basic physics of ion-matter interactions, from the perspectve of damage induced by the beam during Ion Beam Analysis, is presented at a level suitable for post-graduate students. The specificities of damage induced in widely used IBA techniques such as Backscattering Spectrometry (RBS), Nuclear Reaction Analysis (NRA), Elastic Recoil Detection Analysis (ERDA) and Particle-Induced X-ray Emission (PIXE) are presented, followed by sections on damage induced during analysis of different classes of materials such as metals, semiconductors or polymers. A comprehensive bibliography is included

Control of the reactivity at a metal/silica interface

International audienceThe reactivity at the Mo/SiO2 interface is studied as a function of the method of preparation of the silica layer. Three preparation methods for the silicon substrate are considered: plasma-enhanced chemical vapor deposition, and wet and dry thermal oxidations. Respective hydrogen contents in the silica layer of 3.4, 0.5, and 0.4 at. % are induced. We report on the formation of molybdenum silicides (MoSi2 and Mo5Si3) at the Mo/SiO2 interfaces from an x-ray emission spectroscopy study of the interfacial Si 3p occupied valence states. The interfacial reactivity increases with the hydrogen content of the silica film, which is explained by the ease with which the Si-H bonds break during the early stage of the deposition of the metal by cathodic sputtering. (c) 2005 American Institute of Physics

Effet de vicinage pour clusters d’hydrogène traversant la matière : non-linéarité, fluctuations, et explosion coulombienne picoseconde

International audienc

Nanostructuring the Er–Yb distribution to improve the photoluminescence response of thin films

3 pages, 3 figures, 1 table.Thin films of amorphous aluminum oxide (a-Al2O3) codoped with Er3+ and Yb3+ ions have been in-depth nanostructured by distributing the rate earth (RE) ions in layers separated in the 0–3 nm range. The Yb to Er concentration ratio is varied from 0 to 3.6. The photoluminescence (PL) response at 1.53 µm exhibits an increase of up to two orders of magnitude with respect to that of films doped only with Er. The PL intensity is improved when Yb3+ and Er3+ ions are in separate layers and the results show that efficient Yb3+ to Er3+ energy transfer can be achieved for separations up to 3 nm. Furthermore, it is shown that designing an adequate RE distribution, for the same total RE content and Yb to Er concentration ratio, can enhance the PL intensity by a further factor of two. It is shown that the Er3+ PL response is improved because of a reduction of the RE clustering and an improvement of the energy transfer from Yb3+ to Er3+ ions.This work was supported by CICYT (Spain) under TIC2002-03235 Project.Peer reviewe

The role of Er3+–Er3+ separation on the luminescence of Er–doped Al2O3 films prepared by pulsed laser deposition

3 pages, 3 figures, 1 table.Erbium-doped Al2O3 films have been deposited in a single step process by pulsed laser deposition using independent ablation of Al2O3 and Er targets. This procedure allows to control the Er3+ ions in-depth distribution. The characteristic Er3+ photoluminescence at 1.54 μm shows lifetime values which increase from 6.0 to 7.1 ms when the Er3+–Er3+ in-depth separation is increased from 3 to 9 nm. These results are discussed in terms of the ion–ion interaction and clustering for separations shorter than 6 nm.This work was supported by CICYT (Spain) under TIC96-0467 project and by GDR86 of the CNRS (France).Peer reviewe

Enhanced Luminescence Performance by Controlling the Er and Yb Distribution in the Nanometer Scale

CLEO/EUROPE ; EQEC European Quantum Electronics Conference, Munich ICm, Germany, 22-27 June, 2003N