Observations were made, using synchrotron white beam X-ray topography, of stacking faults in 4H–SiC with fault vectors of kind 1/6<20•3>. A mechanism was postulated for their formation which involves overgrowth by a macrostep of the surface outcrop of a c-axis threading screw dislocation, with two c/2-height surface spiral steps, which has several threading dislocations of Burgers vector c+a, with c-height spiral steps, which protrude onto the terrace in between the c/2-risers. Such overgrowth processes deflect the threading dislocations onto the basal plane, enabling them to exit the crystal and thereby providing a mechanism to lower their densities.

Stacking Faults Created by the Combined Deflection of Threading Dislocations of Burgers Vector c and c+a during the Physical Vapor Transport Growth of 4H–SiC. M.Dudley, F.Wu, H.Wang, S.Byrappa, B.Raghothamachar, G.Choi, S.Sun, E.K.Sanchez, D.Hansen, R.Drachev, S.G.Mueller, M.J.Loboda: Applied Physics Letters, 2011, 98[23], 232110