Methods were proposed here for reducing micropipes. Restriction of screw dislocations and decrease of inclusions were the key factors to reduce the number of micropipes. (00▪1) Si-face, (11▪0) and (1¯1▪0) crystal faces acted as growth surface in different experiments. Active C was appended to act as C source. The crucible and active C were subjected to X-ray diffraction investigation before and after growth. The experimental results indicated that the activity of the graphite crucible was low, and it decreased with the progressing crystal growth, which increased the probability of micropipe formation. Appending active C could act as ample C source for crystal growth. The reduction of micropipes was achieved by the restrained formation of Si liquid phase. Using (11▪0) and (1¯1▪0) crystal faces as the growth surfaces the generation of micropipes was restricted, as no new micropipe generated on the (11▪0) and (1¯1▪0) crystal faces. At the same time, the density of edge dislocations was reduced considerably.

Methods for the Reduction of the Micropipe Density in SiC Single Crystals. J.L.Liu, J.Q.Gao, J.K.Cheng, J.F.Yang, G.J.Qiao: Journal of Materials Science, 2007, 42[15], 6148-52