Synchrotron X-ray Topography Studies of the Evolution of the Defect Microstructure in Physical Vapor Transport Grown 4H-SiC Single Crystals

Abstract

Synchrotron White Beam X-ray Topography studies are presented of dislocation behavior and interactions in a new generation of 100mm diameter, 4H-SiC wafers grown using Physical Vapor Transport under specially designed low stress conditions. Such low stress growth conditions have enabled reductions of dislocation density by two or three orders of magnitude from lowest previously reported levels of 104-105cm-2 down to current levels of 102-103 cm-2. This provides a unique opportunity to discern the details of dislocation configurations and interactions which were previously precluded due to complications of image overlap at higher dislocation densities. Detailed topography analysis have revealed dislocation multiplication by the hopping Frank-Read source mechanism, interactions between threading c, a and c+a dislocations and deflections of threading dislocations resulting in stacking fault formation. These insights greatly aid in eliminating such undesirable defects or engineering their structures to minimize their impact leading to improved performance in device applications.