Origin Analyses of Obtuse Triangular Defects in 4deg.-off 4H-SiC Epitaxial Wafers by Electron Microscopy and by Synchrotron X-ray Topography

Triangular shaped defects with obtuse-angles at the vertex and long base are often observed in surfaces of epitaxial films. We have investigated the origins of them, and it became clear that these defects without well defined origins were formed by contaminations of tantalum carbide particles. Formations of micron-order pipes at the points of origin these defects were also observed. These micron-order pipes were not accompanied by strain and dislocations around them, though their appearances were very similar to the so-called micro-pipes.