A process was developed for growing micropipe-free single crystals by using a modified Lely method. The process parameters were kept near to thermal equilibrium. The maximum average thermal gradient, inside the furnace, which led to micropipe-free growth was 5K/cm. A gradient of 7.5K/cm resulted in marked defect formation and produced a high density of micro-pipes (greater than 200/cm2). The highest growth rate here which provided micro-pipe-free growth was 0.27mm/h. Single boule crystals of 6H-material were grown on both the C face and the Si face of 6H-SiC Lely platelets.

N.Schulze, D.L.Barrett, G.Pensl: Applied Physics Letters, 1998, 72[13], 1632-4