Transmission Electron Microscopy Analysis of a Threading Dislocation with $c+a$ Burgers Vector in 4H-SiC

Abstract

A threading dislocation (TD) in 4H-SiC, which was interpreted as a right-handed threading screw dislocation (TSD) by synchrotron monochromatic-beam X-ray topography (SMBXT) and molten KOH etching with Na2O2 additive (KN etching), was characterized by large-angle convergent-beam electron diffraction (LACBED) and weak-beam dark-field methods. It was found that this TD was a so-called c+a dislocation with Burgers vector of b=[0001]+(1/3)[2110], which is often misinterpreted as TSD (c-dislocation) by SMBXT and KN etching. The rotation direction of the screw component within the c+a TD determined by LACBED agreed with the SMBXT observation.