Reduction of dislocation density of SiC crystals grown on seeds after H2 etching

Three-inch 6H-SiC bulk crystals were grown by the PVT method on the seeds processed by different treatments. The influences of seed surface morphology and subsurface damage on the dislocation density were investigated. The seed surface morphology was characterized by atomic force microscopy (AFM). The extent of the subsurface damage was estimated by electron back-scattered diffraction (EBSD) and Band Contrast (BC) value. The distribution and density of the dislocations were observed by optical microscopy (OM). The results showed that the pit density performed by H2 1400°C etching was nearly one order of magnitude lower than that by mechanical polishing (MP) process. So H
₂
etching processed at 1400°C for 2h could completely remove the subsurface damage, compared with the MP process with the deep surface damage.