Papers by Author: François Cauwet

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Authors: P. Dupel, Thierry Chassagne, Didier Chaussende, Yves Monteil, François Cauwet, Etienne Bustarret, A. Deneuville, G. Bentoumi, Eugénie Martinez, B. Daudin, G. Feuillet
Authors: Didier Chaussende, Christophe Jacquier, Gabriel Ferro, Jean Claude Viala, François Cauwet, Yves Monteil
Authors: Kassem Alassaad, Veronique Soulière, François Cauwet, Davy Carole, Gabriel Ferro
Abstract: The interaction of liquid Ge and Si droplets, deposited by CVD, on the surface of 4H-SiC single-crystals is studied. It was found that at 1500 °C Ge forms micrometric droplets while Si forms nanometric dots. While the Si dots do not seem to interact significantly with SiC, the Ge droplets have the tendency to dissolve the Si from the seed. This mechanism not only happens during deposition but also during the cooling. If the cooling rate is too slow, Ge evaporates from the droplets while dissolving Si so that, at the end, the droplets look like to have been fully converted from Ge to Si.
Authors: F. Abdoun, Christophe Jacquier, Gabriel Ferro, François Cauwet, Yves Monteil
Authors: Gabriel Ferro, Didier Chaussende, François Cauwet, Yves Monteil
Authors: Stéphane Berckmans, Laurent Auvray, Gabriel Ferro, François Cauwet, Veronique Soulière, Emmanuel Collard, Jean Baptiste Quoirin, Christian Brylinski
Abstract: The crystal growth of 3C-SiC onto silicon substrate by Vapour-Liquid-Solid (VLS) transport has been investigated. In the studied growth configuration, propane feeds a SiGe liquid phase contained in 10 µm-deep etched trenches on the Si substrate. Before SiGe deposition, the substrate surface and the trench walls were coated with a thin (100 - 200 nm) CVD-grown 3C-SiC seeding layer. For the VLS growth, the temperature was increased up to 1280°C, above the SiGe alloy melting point, at which point propane was added to start VLS growth. X-ray diffraction shows that some SiC is grown epitaxially onto the CVD seeding layer. However, cross-section SEM observations have evidenced that SiC has grown as trapezoidal islands and not as an uniform layer. Backscattered electron images also clearly show a deep penetration of germanium into the substrate through the SiC seeding layer. This penetration was found to be strongly reduced when increasing the seeding layer thickness from 100 to 200 nm.
Authors: Kassem Alassaad, François Cauwet, Davy Carole, Veronique Soulière, Gabriel Ferro
Abstract: Abstract. In this paper, conditions for obtaining high growth rate during epitaxial growth of SiC by vapor-liquid-solid mechanism are investigated. The alloys studied were Ge-Si, Al-Si and Al-Ge-Si with various compositions. Temperature was varied between 1100 and 1300°C and the carbon precursor was either propane or methane. The variation of layers thickness was studied at low and high precursor partial pressure. It was found that growth rates obtained with both methane and propane are rather similar at low precursor partial pressures. However, when using Ge based melts, the use of high propane flux leads to the formation of a SiC crust on top of the liquid, which limits the growth by VLS. But when methane is used, even at extremely high flux (up to 100 sccm), no crust could be detected on top of the liquid while the deposit thickness was still rather small (between 1.12 μm and 1.30 μm). When using Al-Si alloys, no crust was also observed under 100 sccm methane but the thickness was as high as 11.5 µm after 30 min growth. It is proposed that the upper limitation of VLS growth rate depends mainly on C solubility of the liquid phase.
Authors: Veronique Soulière, Kassem Alassaad, François Cauwet, Hervé Peyre, Thomas Kups, Jörg Pezoldt, Pawel Kwasnicki, Gabriel Ferro
Abstract: In this paper, we will describe a detailed experimental study on the behavior of Ge incorporation into 4H-SiC during its homoepitaxial growth by CVD. Addition of GeH4 precursor to the standard chemical system SiH4 + C3H8 was investigated as a function of various growth parameters. Its effect on surface morphology, layer quality and purity was followed. All these results will allow proposing an exhaustive picture of Ge incorporation mechanism into 4H-SiC with the possible benefits of such impurity incorporation in the silicon carbide lattice.
Authors: Kassem Alassaad, Veronique Soulière, Beatrice Doisneau, François Cauwet, Hervé Peyre, Davy Carole, Didier Chaussende, Gabriel Ferro
Abstract: This paper presents the results obtained after chemical vapor deposition of SiC with the addition of GeH4 gas to the classical SiH4+C3H8 precursor system. Epitaxial growth was performed either on 8°off-axis or on-axis 4H-SiC substrate in the temperature range 1500-1600°C. In the off-axis case, the layer quality (surface morphology and defect density) does not change though accompanied with Ge droplets accumulation at the surface. The Ge incorporation level was found to increase with temperature in the 1017 1018 cm-3 ranges. It was observed that adding GeH4 leads to the increase of the n type doping level by a factor from 2 to 5 depending on the C/Si ratio. In the on-axis case, GeH4 was only added to the gas phase before starting the SiC growth. It was found that there is a conditions window (temperature and GeH4 flux) for which 3C-SiC twin free layers can be grown. Adding this foreign element before SiC growth clearly modifies SiC nucleation on on-axis substrate.
Authors: Christophe Jacquier, Gabriel Ferro, Carole Balloud, Marcin Zielinski, Jean Camassel, Efstathios K. Polychroniadis, J. Stoemenos, François Cauwet, Yves Monteil
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