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Study of defect structures in 6H-SiC a/m -plane pseudofiber crystals grown by hot-wall CVD epitaxy
Structural perfection of silicon carbide (SiC) single crystals is essential to achieve high-performance power devices. A new bulk growth process for SiC proposed by researchers at NASA Glenn Research Center, called large tapered crystal (LTC) growth, based on axial fiber growth followed by lateral expansion, could produce SiC boules with potentially as few as one threading screw dislocation per wafer. In this study, the lateral expansion aspect of LTC growth is addressed through analysis of lateral growth of 6H-SiC a/m -plane seed crystals by hot-wall chemical vapor deposition. Preliminary synchrotron white-beam x-ray topography (SWBXT) indicates that the as-grown boules match the polytype structure of the underlying seed and have a faceted hexagonal morphology with a strain-free surface marked by steps. SWBXT Laue diffraction patterns of transverse and axial slices of the boules reveal streaks suggesting the existence of stacking faults/polytypes, and this is confirmed by micro-Raman spectroscopy. Transmission x-ray topography of both transverse and axial slices reveals inhomogeneous strains at the seed–epilayer interface and linear features propagating from the seed along the growth direction. Micro-Raman mapping of an axial slice reveals that the seed contains high stacking disorder, while contrast extinction analysis (g·b and g·b×l) of the linear features reveals that these are mostly edge-type basal plane dislocations. Further high-resolution transmission electron microscopy investigation of the seed–homoepilayer interface also reveals nanobands of different SiC polytypes. A model for their formation mechanism is proposed. Lastly, the implication of these results for improving the LTC growth process is addressed.
Radiation damage reduction by grain-boundary biased defect migration in nanocrystalline Cu
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Ultra-high strength and plasticity mediated by partial dislocations and defect networks: Part I: Texture effect
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Risk comparison for prenatal use of analgesics and selected birth defects, National Birth Defects Prevention Study 1997–2011
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Nanoscale origin and evolution of kinetically induced defects in carbon spheres
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Impact of carbon nanotube defects on fracture mechanisms in ceramic nanocomposites
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Exciton dynamics in cation-exchanged CdSe/PbSe nanorods: The role of defects
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Visualizing MICP with X-ray μ-CT to enhance cement defect sealing
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Theoretical study of defects Cu 3 SbSe 4 : Search for optimum dopants for enhancing thermoelectric properties
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