Defect origin and development in sublimation grown SiC boules

SiC boules were grown by the modified Lely method. Macro-defects in the boules and wafers cut from them were studied by means of optical microscopy and chemical etching. The influence of the quality, the surface orientation and attachment of the seed crystal on secondary evaporation, domain and micropipe formation was studied. The results obtained are discussed in terms of defect development at different stages of the crystal growth and under different growth conditions.