Microscopic Structure of Stepwise Threading Dislocation in 4H-SiC Substrate

The dislocation structure that forms the caterpillar-shaped etch pit upon molten KOH etching is investigated by transmission electron microscopy employing a weak-beam dark-field method. The observed dislocation has the Burgers vector 1/3[(1) over bar2 (1) over bar0], and its structure was transformed from a basal plane dislocation to a threading edge dislocation. In the basal plane dislocation region, it propagated parallel to the [10 (1) over bar0] direction. On the basis of the measured dislocation structure, the caterpillar pit formation is explained. The process of dislocation formation is discussed by analyzing the relationship between sample types and the detection of the caterpillar pits. (C) 2012 The Japan Society of Applied Physics