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6H-SiC and 3C-SiC single crystals were simultaneously irradiated at room temperature with 100-keV Fe ions at fluences up to 4x10 13 cm-2 (~0.7 dpa), i.e. up to amorphization. The disordering behaviour of both polytypes has been investigated by means of Rutherford backscattering spectrometry in the channelling mode and synchrotron X-ray diffraction. For the first time, it is experimentally demonstrated that the general damage build-up is similar in both polytypes. At low dose, irradiation induces the formation of small interstitial-type defects. With increasing dose, amorphous domains start to form at the expense of the defective crystalline regions. Full amorphization of the irradiated layer is achieved at the same dose (~0.45 dpa) for both polytypes. It is also shown that the interstitial-type defects formed during the first irradiation stage induce a tensile elastic strain (up to ~3.8%) to which is associated an elastic energy. It is conjectured that this stored energy destabilizes the current defective microstructure observed at low dose and stimulates the formation of the amorphous nanostructures at higher dose. Finally, the disorder accumulation has been successfully reproduced with two models (namely MSDA and DI/DS). Results obtained from this modelling are compared and discussed in the light of experimental data.

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Large scale, homogeneous quasi-free standing monolayer graphene is obtained on cubic silicon carbide, i.e. the 3C-SiC(111) surface, which represents an appealing and cost effective platform for graphene growth. The quasi-free monolayer is produced by intercalation of hydrogen under the interfacial, (6root3x6root3)R30-reconstructed carbon layer. After intercalation, angle resolved photoemission spectroscopy (ARPES) reveals sharp linear pi-bands. The decoupling of graphene from the substrate is identified by X-ray photoemission spectroscopy (XPS) and low energy electron diffraction (LEED). Atomic force microscopy (AFM) and low energy electron microscopy (LEEM) demonstrate that homogeneous monolayer domains extend over areas of hundreds of square-micrometers.Comment: 4 pages, 3 figures, Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physic

To achieve AlN bulk growth, high temperature CVD process using chlorine chemistry was investigated. High growth rate and high crystalline quality are targeted for both polycrystalline and epitaxial AlN films grown on (0 0 0 1) alpha-Al2O3 Sapphire and (0 0 0 1) off axis 4H SiC or on axis 6H SiC single crystal Substrates. Thermodynamic calculations were carried out to select the more appropriate inert materials for the reactor and to understand the chemistries of Al chlorination and AlN deposition steps. The reactants were ammonia (NH3) and aluminum chlorides (AlClx) species formed in situ using chlorine gas (Cl-2) reaction with high purity Al wires. Deposition temperature was varying from 1100 to 1800 degrees C. Influences of temperature, total pressure, Cl-2 flow rate and carrier gas (Ar or H-2) on growth rate, surface morphology and crystalline state are presented. As results, films morphology is related to a variation of the thermodynamic supersaturation. As-grown AlN layers surface morphologies were studied by SEM, FEG-SEM and AFM. Crystalline state, crystallographic orientations and epitaxial relationships with substrates were obtained from theta/2 theta X-ray diffraction and X-ray pole figure, respectively. Growth rates up to 200 mu m h(-1) have been reached for polycrystalline AlN layers. (C) 2009 Elsevier B.V. All rights reserved

Expérience GANIL/ARIBEThe healing effect of intense electronic energy deposition arising during swift heavy ion (SHI) irradiation is demonstrated in the case of 3C-SiC damaged by nuclear energy deposition. Experimental (ion channeling experiments) and computational (molecular dynamics simulations) studies provide consistent indications of disorder decrease after SHI irradiation. Furthermore, both methods establish that SHI-induced recrystallization takes place at amorphous-crystalline interfaces. The recovery process is unambiguously accounted for by the thermal spike phenomenon

International audienceThe micropipe-induced birefringence of 6H silicon carbide (SiC) is measured and quantitatively modelled. A good agreement can be obtained between theory and experiment, provided that background residual stress is added to the local dislocation-induced stress. Observations are compatible with or predictable from the Burgers vector values, and birefringence is shown to be an interesting tool for probing the nature of the dislocations associated with e. g. micropipes; it is also faster than and complementary to the more involved techniques of transmission electron microscopy or X-ray topography

International audienceNew experimental results supported by theoretical analyses are proposed for aluminum silicon carbide(Al4SiC4). A state of the art implementation of the density functional theory is used to analyze the experimental crystal structure, the Born charges, the elastic properties, and the piezoelectricproperties. The Born charge tensor is correlated to the local bonding environment for each atom. The electronic band structure is computed including self-consistent many-body corrections. Al4SiC4material properties are compared to other wide band gap wurtzite materials. From a comparison between an ellipsometry study of the optical properties and theoretical results, we conclude that the Al4SiC4material has indirect and direct band gapenergies of about 2.5 eV and 3.2 eV, respectively