Crystallographic structures of 8H-and 10H-SiC crystals were analyzed by the Raman spectroscopy and diffraction methods. Two and four transverse-optical modes for 8H-and 10H-SiC were observed, and their values were different from those of 4H-and 6H-SiC. Crystallinity for the wide and narrow areas of these crystals was analyzed by the Laue diffraction and the transmission electron microscope, respectively. Based on these results, the stacking sequences of these polytype were discussed.
A possibility for using an apple undulator to generate a photon beam with transverse optical modes