Cross-polarization imaging and micro-raman detection of defects in the epitaxy of 4H-SiC

Cross-polarized imaging with an optical scanner and confocal mu-Raman spectroscopy have been used to reveal and to study structural defects in n-4H-SiC. We introduce a new method of polarized imaging that uses a combination of linear and circular polarization, which enhances contrast in images of defect regions. Regions that show intensity contrast have been observed to have characteristics of either low-angle grain boundaries or sharp lines of delineation between low and high strain areas. Different types of polytype inclusions have also been observed, and the material within the inclusions has been shown to be either 3C-SiC or 6H-SiC. Polytype inclusions occur as isolated features or form cores of holes, and they can form at any point of the growth.