The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
E. Bustarret - One of the best experts on this subject based on the ideXlab platform.
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Stratigraphy of a diamond epitaxial three-dimensional overgrowth using doping superlattices
Applied Physics Letters, 2016Co-Authors: F Lloret, A Fiori, D Araujo, D. Eon, M.p. Villar, E. BustarretAbstract:The selective doped overgrowth of 3D mesa patterns and trenches has become an essential fabrication step of advanced monolithic diamond-based power devices. A novel methodology is proposed here, combining the overgrowth of plasma-etched cylindrical mesa structures with the sequential growth of doping superlattices. The latter involve thin heavily boron doped epilayers separating thicker undoped epilayers in a periodic fashion. Beside the classical shape analysis under the scanning electron microscope relying on the appearance of facets corresponding to the main crystallographic directions and their evolution toward slow growing facets, the doping superlattices were used as markers in oriented cross-sectional lamellas prepared by Focused Ion Beam and observed by Transmission Electron Microscopy. This stratigraphic approach is shown here to be applicable to overgrown structures where faceting was not detectable. Intermediate growth directions were detected at different times of the growth process and the periodicity of the superlattice allowed to calculate the growth rates and parameters, providing an original insight into the planarization mechanism. Different configurations of the growth front were obtained for different sample orientations, illustrating the anisotropy of the 3D growth. Dislocations were also observed along the lateral growth fronts with two types of Burger Vector: bsub01-1 = 1/2 [01-1] and bsub112 = 1/6 [112]. Moreover, the clustering of these extended defects in specific regions of the overgrowth prompted a proposal of two different dislocation generation mechanisms.
Marc Legros - One of the best experts on this subject based on the ideXlab platform.
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extended defect change in uo2 during in situ tem annealing
Acta Materialia, 2020Co-Authors: C Onofri, C Sabathier, Cedric Baumier, C Bachelet, D Drouan, Marie Gerardin, Marc LegrosAbstract:Abstract Predicting the nuclear fuel microstructure at each moment of its irradiation cycle (nominal, power transient, accidental conditions) is a significant nuclear safety issue. For that, it is necessary to understand the impact of irradiation parameters on the microstructure. This study provides insight about the temperature effect on dislocations. In situ thermal annealing up to 1400°C on pre-irradiated polycrystalline UO2 thin foils was performed inside a TEM for the first time. The aim of the current study is to establish the kinetic and the mechanisms of thermal recovery of extended defects induced by irradiation. Whatever the initial irradiation conditions, extended defect recovery was observed around 1000-1100°C, in good agreement with literature data. Dislocation line disappear mainly by climb and dislocation loops move by pencil glide along the Burger Vector directions. Defect growth by coalescence of dislocation loops is also observed.
F Lloret - One of the best experts on this subject based on the ideXlab platform.
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Stratigraphy of a diamond epitaxial three-dimensional overgrowth using doping superlattices
Applied Physics Letters, 2016Co-Authors: F Lloret, A Fiori, D Araujo, D. Eon, M.p. Villar, E. BustarretAbstract:The selective doped overgrowth of 3D mesa patterns and trenches has become an essential fabrication step of advanced monolithic diamond-based power devices. A novel methodology is proposed here, combining the overgrowth of plasma-etched cylindrical mesa structures with the sequential growth of doping superlattices. The latter involve thin heavily boron doped epilayers separating thicker undoped epilayers in a periodic fashion. Beside the classical shape analysis under the scanning electron microscope relying on the appearance of facets corresponding to the main crystallographic directions and their evolution toward slow growing facets, the doping superlattices were used as markers in oriented cross-sectional lamellas prepared by Focused Ion Beam and observed by Transmission Electron Microscopy. This stratigraphic approach is shown here to be applicable to overgrown structures where faceting was not detectable. Intermediate growth directions were detected at different times of the growth process and the periodicity of the superlattice allowed to calculate the growth rates and parameters, providing an original insight into the planarization mechanism. Different configurations of the growth front were obtained for different sample orientations, illustrating the anisotropy of the 3D growth. Dislocations were also observed along the lateral growth fronts with two types of Burger Vector: bsub01-1 = 1/2 [01-1] and bsub112 = 1/6 [112]. Moreover, the clustering of these extended defects in specific regions of the overgrowth prompted a proposal of two different dislocation generation mechanisms.
C Onofri - One of the best experts on this subject based on the ideXlab platform.
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extended defect change in uo2 during in situ tem annealing
Acta Materialia, 2020Co-Authors: C Onofri, C Sabathier, Cedric Baumier, C Bachelet, D Drouan, Marie Gerardin, Marc LegrosAbstract:Abstract Predicting the nuclear fuel microstructure at each moment of its irradiation cycle (nominal, power transient, accidental conditions) is a significant nuclear safety issue. For that, it is necessary to understand the impact of irradiation parameters on the microstructure. This study provides insight about the temperature effect on dislocations. In situ thermal annealing up to 1400°C on pre-irradiated polycrystalline UO2 thin foils was performed inside a TEM for the first time. The aim of the current study is to establish the kinetic and the mechanisms of thermal recovery of extended defects induced by irradiation. Whatever the initial irradiation conditions, extended defect recovery was observed around 1000-1100°C, in good agreement with literature data. Dislocation line disappear mainly by climb and dislocation loops move by pencil glide along the Burger Vector directions. Defect growth by coalescence of dislocation loops is also observed.
D Araujo - One of the best experts on this subject based on the ideXlab platform.
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Stratigraphy of a diamond epitaxial three-dimensional overgrowth using doping superlattices
Applied Physics Letters, 2016Co-Authors: F Lloret, A Fiori, D Araujo, D. Eon, M.p. Villar, E. BustarretAbstract:The selective doped overgrowth of 3D mesa patterns and trenches has become an essential fabrication step of advanced monolithic diamond-based power devices. A novel methodology is proposed here, combining the overgrowth of plasma-etched cylindrical mesa structures with the sequential growth of doping superlattices. The latter involve thin heavily boron doped epilayers separating thicker undoped epilayers in a periodic fashion. Beside the classical shape analysis under the scanning electron microscope relying on the appearance of facets corresponding to the main crystallographic directions and their evolution toward slow growing facets, the doping superlattices were used as markers in oriented cross-sectional lamellas prepared by Focused Ion Beam and observed by Transmission Electron Microscopy. This stratigraphic approach is shown here to be applicable to overgrown structures where faceting was not detectable. Intermediate growth directions were detected at different times of the growth process and the periodicity of the superlattice allowed to calculate the growth rates and parameters, providing an original insight into the planarization mechanism. Different configurations of the growth front were obtained for different sample orientations, illustrating the anisotropy of the 3D growth. Dislocations were also observed along the lateral growth fronts with two types of Burger Vector: bsub01-1 = 1/2 [01-1] and bsub112 = 1/6 [112]. Moreover, the clustering of these extended defects in specific regions of the overgrowth prompted a proposal of two different dislocation generation mechanisms.
