Growth conditions and in situ computed tomography analysis of facetted bulk growth of SiC boules

Two 3inch SiC boules were grown in a PVT setup using source material of different packing density. During the growth, in-situ computed tomography of the growing boules showed differences in the development of the growth interface. A slightly bent growth interface was found for the smaller packing density. For the higher packing density the resulting crystal exhibits the onset of 6 pyramidal facets on its flanks. Besides that, strong anisotropic lateral growth was found on its (000-1) facet. Numerical simulations show an impact of the powder on the thermal gradient in the growth cell and therefore on the supersaturation. It is discussed that a higher supersaturation can account for the anisotropy in the growth rate of the [1-100] and the [11-20] direction.