Reflection and transmission X-ray topographic study of a SiC crystal and epitaxial wafer

Defects in commercially available silicon carbide (SiC) wafers have been investigated by X-ray topography and optical microscopy. Dots appearing in transmission topographs are identified as a screw dislocation running through the [0001] direction by a comparative observation of the reflection topographs from the front and rear sides. In the peripheral region, these dots appear with high density and accompany large strain fields at the edge, which are related with the dislocations in the basal plane emanating from the dots and connecting them and large holes with diameters of about 10–20 μm opening at the epilayer surface. These large strain fields are considered to originate from the large Burgers vector associating with the screw dislocations.