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 tops and long bases are often observed in surfaces of epitaxial films. We have investigated the origins of them, and it became clear that these defects without clear origins were formed by contaminations of tantalum carbide particles. Formations of micro-order pipes at the origin points of these defects were also observed. These micro-order pipes did not accompany strain and dislocations around them, though their appearances were very similar to the ones so-called micro-pipes.