Synchrotron X-ray topography analysis of the distribution and formation mechanisms of low angle grain boundaries in PVT-Grown 4H-SiC Crystal

Abstract

Analysis of the distribution and formation mechanisms of low-angle grain boundaries (LAGBs) in physical vapor transport (PVT) grown 4H-SiC crystals was conducted by synchrotron monochromatic beam x-ray topography (SMBXT) in conjunction with ray-tracing simulation of dislocation images. Threading edge dislocation (TED)-LAGB networks were observed inside the facet region and next to the facet. Identification of TED Burgers vectors is achieved by correlating the ray tracing simulation and the observed contrast configurations from topographs. The results suggest that the TED-LAGBs network in the facet region originates from misorientations between threading screw dislocations which act as growth centers in the region. The LAGB network next to the facet results from the interaction of growth fronts of horseshoe-shaped steps from small spikes from the facet. This network incorporates prismatic slip dislocations induced by radial temperature gradients. These findings provide a novel mechanism for TED-LAGB formation, correlating the spatial distribution and growth dynamics.

Keywords: 4H-SiC, Low-angle grain boundary, Synchrotron x-ray topography