Structural Characterization of the Growth Front of 4H-SiC Boules Grown Using the Physical Vapor Transport Growth Method
Masashi SonodaKentaro ShiouraTakahiro NakanoNoboru OhtaniMasakazu KatsunoHiroshi TsugeShinya SatoTatsuo Fujimoto
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Abstract:
The defect structure at the growth front of 4H-SiC boules grown using the physical vapor transport (PVT) method has been investigated using high resolution x-ray diffraction and x-ray topography. The crystal parameters such as the c -lattice constant exhibited characteristic variations across the growth front, which appeared to be caused by variation in surface morphology of the as-grown surface of the boules rather than the defect structure underneath the surface. X-ray topography also revealed that basal plane dislocations are hardly nucleated at the growth front during PVT growth of 4H-SiC crystals.Keywords:
Basal plane
Lattice constant
Characterization
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Oceanic front is an important phenomenon and is of great significance for research.Although the surface thermal front to the east of Taiwan is not obvious,there is an all-year strong Kuroshio thermal front under the surface,the research on which is rare at this time.Reanalysis method was used in this study to demonstrate the existence of thermal front in this area,study the temporal and spatial variation of the Kuroshio front and discuss the mechanism of frontogenesis.
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Abstract World War I was fought on many fronts, none more enormous than the Eastern Front. The geographic scale alone was mammoth, and the casualties inflicted and losses in equipment were equally immense. In its conduct, the war on the Eastern Front was quite different from the Western Front; while operations on the Western Front assumed a stationary character between the mobile campaigns of 1914 and the return of mobility in 1918, the Eastern Front was different. In the East, the war remained mobile throughout, with large swaths of territory (and the people inhabiting them) changing hands on a regular basis. Finally, in a political sense, the war on the Eastern Front was far more destructive than the Western Front. Of the three political regimes that went to war on the Eastern Front in 1914, none remained by the end of 1918.
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Lattice constant
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It is shown that the Fraunhofer approximation, used in the kinematical theory of X-ray diffraction, may fail for a wide variety of crystals with different perfection. The kinematical theory describing the diffraction pattern in the general case is developed. The case of spherical-wave diffraction by a plane parallel crystal is considered in detail. The intensity distribution and the diffraction line width are ascertained to be essentially dependent on the region of diffraction in which the observation plane is located. On the other hand, the diffraction pattern geometry is independent of the diffraction region and is determined only by the crystal structure and the optics of diffraction. The geometry of the diffraction pattern recorded by the divergent-beam method is analysed in detail.
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