Characterization of triangular-defects in 4°off 4H-SiC epitaxial wafers by synchrotron X-ray topography and by transmission electron microscopy

We have investigated origins and structures of triangular-shaped defects formed on surfaces of 4-degrees-off 4H-SiC epitaxial wafers. It is well known that some of the triangular-shaped defects are originated by 3C-SiC particles so called "downfalls", but major origins of the defects have been unknown until now. Our TEM observations show that not only anomalous grain formations of SiC in epitaxial films, but also contaminations by foreign materials can be the origins of the defects. Several different types of structure for the isosceles triangular-shaped defects investigated by synchrotron X-ray topography experiments are also reported. It is discussed that there exist different types of Burgers vectors configurations at the interface between epitaxial films and triangular defects.