Transmission electron microscopy, high-resolution X-ray diffraction and KOH-etching techniques were used to study dislocations in crystals of 4H-type material which had been grown via physical vapour transport. Many of the etch pits formed arrays which extended along the <11•0> and <¯11•0> directions on (00•1) wafers. Plan-view and high-resolution transmission electron microscopy showed that both types of array consisted of pure edge dislocations which threaded along the c-axis, and had identical Burgers vectors of a/3<11•0> type. The former arrays were interpreted as being slip bands which were formed by dislocation glide on the <11•0>{¯11•0} slip system of the hexagonal phase during post-growth cooling. The latter arrays made up low-angle tilt boundaries with their tilt axis parallel to the [00•1] direction. It was shown that such boundaries could form via polygonization of the threading edge dislocations which were introduced by plastic deformation.

Origin of Threading Dislocation Arrays in SiC Boules Grown by PVT S.Ha, N.T.Nuhfer, M.De Graef, G.S.Rohrer, M.Skowronski: Materials Science Forum, 2000, 338-342, 477-80