Châteauneuf-Grasse, France
Châteauneuf-Grasse, France

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Process for treating and receptacle for confining an anode, wherein the anode is placed in a confining receptacle that envelops this anode while leaving uncovered an annular coating zone of a frontal face of this anode, which is defined by an aperture of the receptacle; in order to carry out a least one operation for treating said annular coating zone, implementing at least one treating gas.


Balaji M.,Grenoble Institute of Technology | Balaji M.,Anna University | Claudel A.,ACERDE | Fellmann V.,Grenoble Institute of Technology | And 12 more authors.
Journal of Alloys and Compounds | Year: 2012

AlN layers were grown on c-plane sapphire substrates with AlN nucleation layers (NLs) using high temperature hydride vapor phase epitaxy (HT-HVPE). Insertion of low temperature NLs, as those typically used in MOVPE process, prior to the high temperature AlN (HT-AlN) layers has been investigated. The NLs surface morphology was studied by atomic force microscopy (AFM) and NLs thickness was measured by X-ray reflectivity. Increasing nucleation layer deposition temperature from 650 to 850 °C has been found to promote the growth of c-oriented epitaxial HT-AlN layers instead of polycrystalline layers. The growth of polycrystalline layers has been related to the formation of dis-oriented crystallites. The density of such disoriented crystallites has been found to decrease while increasing NLs deposition temperature. The HT-AlN layers have been characterized by X-ray diffraction θ - 2θ scan and (0 0 0 2) rocking curve measurement, Raman and photoluminescence spectroscopies, AFM and field emission scanning electron microscopy. Increasing the growth temperature of HT-AlN layers from 1200 to 1400 °C using a NL grown at 850 °C improves the structural quality as well as the surface morphology. As a matter of fact, full-width at half-maximum (FWHM) of 0 0 0 2 reflections was improved from 1900 to 864 arcsec for 1200 °C and 1400 °C, respectively. Related RMS roughness also found to decrease from 10 to 5.6 nm. © 2011 Elsevier Ltd. All rights reserved.


Boichot R.,Grenoble Institute of Technology | Coudurier N.,Grenoble Institute of Technology | Mercier F.,Grenoble Institute of Technology | Claudel A.,ACERDE | And 4 more authors.
Theoretical Chemistry Accounts | Year: 2014

This study presents numerical modeling based on a relatively limited number of gas-phase and surface reactions to simulate the growth rate of aluminum nitride layers on AlN templates and c-plane sapphire in a broad range of deposition parameters. Modeling results have been used to design particular experiments in order to understand the influence of the process parameters on the crystal quality of AlN layers grown in a high-temperature hydride vapor-phase epitaxy process fed with NH3, AlCl3, and H2. Modeling results allow to access to very interesting local quantities such as the surface site ratio and local supersaturation. The developed universal model starting from local parameters might be easily transferred to other reactor geometry and process conditions. Among the investigated parameters (growth rate, temperature, local supersaturation, gas-phase N/Al ratio, and local surface site N/Al ratio), only the growth rate/supersaturation or growth rate/temperature relationships exhibit a clear process window to use in order to succeed in growing epitaxial AlN layers on c-plane sapphire or AlN templates. Gas-phase N/Al ratio and local surface site N/Al ratio seem to play only a secondary role in AlN epitaxial growth. © Springer-Verlag Berlin Heidelberg 2013.


Boichot R.,Grenoble Institute of Technology | Claudel A.,Acerde | Baccar N.,Grenoble Institute of Technology | Milet A.,DCM Chimie Theorique | And 2 more authors.
Surface and Coatings Technology | Year: 2010

AlN growth by HTCVD (High Temperature Chemical Vapor Deposition) from AlCl3 and NH3 is currently a promising way to obtain thick, compact layers of aluminum nitride. This study focused on the development of a kinetic mechanism that models AlN growth with only 7 gas-phase reactions and 4 surface reactions. Ab initio estimation of the thermodynamic data of the AlCl2NH2, AlClNH, AlCl(NH2)2 and Al(NH2)3 intermediates suspected to be involved in the gas-phase reactions is proposed. It was found that only AlCl2NH2 is present in noticeable concentrations under our experimental conditions. Experiments made at different temperatures and N/Al ratios, carried out in a cold wall HTCVD reactor, were used to validate the proposed model. Finally, the N/Al ratio in the gas phase was observed to play a key role in the AlN surface quality. Possible explanations of this influence and future experiments that will confirm this trend are discussed. © 2010 Elsevier B.V.


Coudurier N.,Grenoble Institute of Technology | Boichot R.,Grenoble Institute of Technology | Fellmann V.,ACERDE | Claudel A.,ACERDE | And 5 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2013

A High Temperature Hydride Vapor Phase Epitaxy reactor (HT-HVPE) was used to grow 5 μm-thick (0001) epitaxial AlN layers on sapphire. The experimental set-up consists of a vertical cold-wall quartz reactor working at low pressure in which the reactions take place on a graphite susceptor heated by induction. The reactants used are ammonia (NH3) and aluminum chlorides (AlClx) in situ formed via chlorine (Cl2) reaction with high purity aluminum pellets. As-grown AlN layers have been characterized by Scanning Electron Microscopy (SEM), X-ray diffraction rocking curves (XRC) and Raman spectroscopy. First, the influence of the V/III ratio in the gas phase on surface morphology, crystalline quality and strain into the material is investigated in order to improve the quality of epitaxial AlN layers grown at high temperature. Parameters were adjusted to keep constant growth rate of about 5 μm/h. Second, a protective layer (growth of a 200 nm-thick AlN layer at 1200 °C) was deposited before the main growth of a 5μm layer of AlN at 1500°C. A 430 arcsec FWHM value for the 0002 reflection of the AlN layer has been obtained for such experimental conditions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Claudel A.,ACERDE | Blanquet E.,Grenoble Institute of Technology | Chaussende D.,Grenoble Institute of Technology | Boichot R.,Grenoble Institute of Technology | And 7 more authors.
Journal of Crystal Growth | Year: 2011

Thick AlN layers were grown by high temperature chemical vapor deposition (HTCVD) on 8° off-axis (0 0 0 1) 4H-SiC, on-axis (0 0 0 1) 6H-SiC and on-axis (0 0 0 1) AlN templates between 900 °C and 1600 °C. The experimental set-up consists of a vertical cold-wall reactor working at low pressure in which the reactions take place on a graphite susceptor heated by induction. The reactants used are ammonia (NH3) and aluminum chlorides (AlClx) species in situ formed via Cl2 reaction with high purity aluminum wire. As-grown AlN layers have been characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Optical Profilometry, Atomic Force Microscopy (AFM) and Raman spectroscopy. In this study, the influence of the deposition temperature and the N/Al ratio in the gas phase is studied in order to stabilize epitaxial growth. The epitaxy on AlN template is favored using a low N/Al ratio in the gas phase and a high temperature above 1400 °C. The crystalline quality of epitaxial AlN layers is found to increase with increasing deposition temperature from 1400 to 1500 °C. Growth rates up to 14 μm h-1 have been reached for epitaxial AlN layers. An important etching phenomenon is also observed at high temperature: apparition of pin holes certainly around threading dislocations at 14001500 °C and substrate etching at 1600 °C. © 2011 Elsevier B.V. All Rights Reserved.


Claudel A.,ACERDE | Chowanek Y.,Grenoble Institute of Technology | Blanquet E.,Grenoble Institute of Technology | Chaussende D.,Grenoble Institute of Technology | And 7 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2011

Due to its wide bandgap (6.2 eV), its high thermal conductivity (3.3 WK-1cm-1) and high electrical resistivity (1013 Ωcm), AlN is a very expected III-N semiconductor for applications in high power electronics (HEMTs) and optoelectronics (UV LEDs). In this work, the homoepitaxial growth of aluminum nitride on polar and non-polar AlN PVT seeds by HTCVD is studied. From our knowledge, the AlN homoepitaxial growth by HVPE or HTCVD on polar and non-polar bulk AlN substrates has not been reported. The potential of investigation in this new range of experiments conditions, i.e. high temperature and high growth rate, as well as the deposition of non-polar AlN crystals (Paskova, Phys. Status Solidi B 245(6), 1011 (2008) and Schwarz and Kneissl, Phys. Status Solidi RRL 1(3), A44 (2007) [1, 2]) is very promising for epitaxial growth and could extend the field of applications. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Pons M.,CNRS Materials Science and Engineering | Boichot R.,CNRS Materials Science and Engineering | Coudurier N.,CNRS Materials Science and Engineering | Claudel A.,Acerde | And 4 more authors.
Surface and Coatings Technology | Year: 2013

The application of AlN films in optoelectronics, sensors and high temperature coatings is strongly dependent on the nano-micro-structure of the film, impurity level and defect density. AlN epitaxial thin (0.5-10μm) and thick polycrystalline (>10μm) films were grown on different foreign substrates (sapphire, silicon carbide, graphite) and single AlN crystals by Chemical Vapor Deposition (CVD), also called Hydride Vapor Phase Epitaxy (HVPE), at high temperature (1200-1750°C). In the first part of this paper, polycrystalline growth of thick films (>10μm) prepared at high growth rate (>100μm·h-1) was performed on graphite substrates to study the preferential orientation of the films. AlN/W multilayers were deposited on silicon carbide composites to increase their performance at high temperature in aggressive conditions. Such multilayer materials can be used for the cladding of nuclear fuel. The second part of this paper concerns the characterization of epitaxial films, including their crystalline state, surface morphology, and inherent and thermally induced stress which inevitably leads to high defect densities and even cracking. The full-width at half-maximum (FWHM) of X-ray rocking curves of the grown AlN layers exhibited very large values (several thousand arcsec), and they became steeply deteriorated with increasing growth rate. To improve the crystalline quality of AlN layer, well-known growth techniques, such as multi-step growth using buffer layers, were used at temperatures above 1200°C in order to lower the disorientation to 300arcsec. The applications of such "templates" for deep UV light emitting diodes (UV LED) and surface acoustic wave sensors (SAW) are discussed. © 2013.


Claudel A.,ACERDE | Blanquet E.,Grenoble Institute of Technology | Chaussende D.,Grenoble Institute of Technology | Boichot R.,Grenoble Institute of Technology | And 8 more authors.
Journal of the Electrochemical Society | Year: 2011

Thick polycrystalline AlN layers were grown at low pressure using high temperature chemical vapor deposition (HTCVD). The experimental setup consists of a graphite susceptor heated by an induction coil surrounding a vertical cold wall reactor. The reactants used were ammonia (N H3) and aluminum chloride (Al Clx) species formed in situ via chlorine (Cl 2) reaction with high purity aluminum wire. AlN films were deposited on a 55 mm diameter graphite susceptor between 1200 and 1600°C. AlN layers have been characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and electron backscattered diffraction. The influence of temperature on growth rate, surface morphology, grain size, and crystalline structure is presented. Growth rates of up to 230 μm/h have been reached. A nonpolar preferred orientation of AlN films is stabilized at a higher temperature. The potential of investigation in this new range of experimental conditions, i.e., high temperature and high growth rate, as well as deposition of nonpolar AlN crystals, is very promising for epitaxial growth and extends the field of applications. © 2011 The Electrochemical Society.


A process for repairing a damaged annular region of an anode configured to emit x-rays includes the step of machining the damaged annular region made of an initial target coating to a depth smaller than a thickness of the coating so as to leave behind a residual annular layer. An intermediate layer is then deposited on the residual annular layer. A repairing layer is then deposited on the intermediate layer. A heat treatment is then performed using an anneal which causes, by interdiffusion and formation of a solid solution, the material of the intermediate layer and the material of the residual annular layer to diffuse into each other and further cause the material of the intermediate layer and the material of the repairing layer diffuse into each other. As a result of this anneal the intermediate layer disappears.

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