Crystals grown by the physical vapour transport process along the [001] direction showed a curvature of the crystal growth front in correspondence with the shape of the isotherms. A large radius for the curvature of the isotherms enhanced the formation of an extended facet. Under the facet, the lattice planes were flat with a high crystal quality as expressed by rocking-curve half widths of 0.022°. In the non-faceted region, the lattice planes became bent, following the shape of the isotherms with a radius of typically 0.5 to 0.8m and an increased rocking-curve half width of 0.3°. A reduction of the growth rate from 300 to 70µm/h did not significantly affect this behaviour. The lattice-plane curvature and the development of the facet were predominantly affected by the shape of the isotherms. For crystals grown in the [015] direction, the lattice planes adjust only in a one-dimensional manner to the isotherms. In all cases, the lattice-plane curvature results from the formation of a high density of small-angle grain boundaries. They were generated by the condensation of dislocations with Burgers vectors in the ab-plane.

Lattice-Plane Curvature and Small-Angle Grain Boundaries in SiC Bulk Crystals. C.Seitz, Z.G.Herro, B.M.Epelbaum, R.Hock, A.Magerl: Journal of Applied Crystallography, 2006, 39[1], 17-23