No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

4H silicon carbide as-grown ingots were investigated by diffraction imaging using synchrotron radiation. The white beam section topographs obtained for various sample geometries allowed us to reveal structural imperfections before slicing the bulky ingots to the thin wafers used as electronic device substrates. The systematic investigation indicated that the observed inclusions of different polytypes in 4H-SiC ingots are correlated with the 8° off-axis orientation of the seed. These inclusions, formed at the beginning of the crystal growth, provoke planar defects that propagate along the main vertical axis of the cylindrical crystal. New findings permitted us to understand the inclusion formation with the aim to increase the useful volume.

In view of its excellent thermal, mechanical and electronic properties, silicon carbide is the reference semiconductor material for high-temperature, highfrequency and high-power devices.Ingots of monocrystalline SiC which are currently grown by the seeded sublimation growth technique have opened the path to the production of largearea SiC wafers. Despite constant progress in crystal growth, the development of industrial applications has been up to now severely limited by the insufficient quality and size of the substrates. This situation results mainly from the fact that the growing process is quite complex. As a consequence, it is quite difficult to control the growth of a given polytype and the doping level while decreasing the number of defects such as misoriented domains, inclusions, macrodefects and micropipes.This paper is mainly devoted to a review of our work on the influence of the seed characteristics and the growth process parameters, such as the thermal field and the pressure, on the occurrence of defects in the as grown ingot and on the enlargement process. Polytype identification and morphology, structural perfection and defect analyses have been carried out using mainly polarized light microscopy and x-ray white-beam synchrotron topography.