The etching morphology of dislocations in 8° off-axis 4H-SiC epilayers was observed by using a scanning electron microscope. It was found that different types of dislocation corresponded to different densities and basal plane dislocation array and threading edge dislocation pile-up group lay along some certain crystal directions in the epilayer. It was concluded that the elastic energy of threading screw dislocations was highest and threading edge dislocations was lowest among these dislocations, so the density of threading screw dislocations was lower than threading edge dislocations. The basal plane dislocations could convert to threading edge dislocations but threading screw dislocations could only propagate into the epilayer in spite of the higher elastic energy than threading edge dislocations. The reason of the form of basal plane dislocations array in epilayer was that the big step along the basal plane caused by face defects blocked the upstream atoms, and threading edge dislocations pile-up group was that the dislocations slide was blocked by dislocation groups in epilayer.

Investigation of Dislocations in 8° Off-Axis 4H-SiC Epilayer. R.X.Miao, Y.M.Zhang, Y.M.Zhang, X.Y.Tang, Q.F.Gai: Chinese Physics B, 2010, 19[7], 076106