Elementary Screw and Mixed-Type Dislocations in 4H-SiC Characterized by X-Ray Topography Taken with Six Equivalent 11-28 <i>g</i>-Vectors and a Comparison to Etch Pit Evaluation

We have studied threading dislocations (TDs) in 4H-SiC by means of X-ray topography (XRT) taken under 6 equivalent g-vector of 11-28 and two different chemical etching methods. Threading screw and mixed-type dislocations (TSDs and TMDs) can be distinguished and the direction of the a-components of TMDs can be determined by XRT. Efforts have been made to examine if there are features of etch pits that can be used to distinguish TMDs from TSDs.