Raman scattering properties of structural defects in SiC

Although silicon carbide crystals have been commercially available, the structural discontinuity in crystal always leads to complex interplay between the atomic positions and the electronic structures, hence results in the crystal reconstructing structurally and electronically. Here we investigate the vibrational properties of 6H-SiC (6H-polytype silicon carbide) crystals containing structural defects, e.g. micropipes (MPs), screw-dislocations (SDs) and threading dislocations (TDs), by Raman scattering. For the first-order Raman scattering, the intensity of the transverse optical phonon band centered at similar to 796 cm(-1), which corresponds to the phonon mode at the Gamma point in 3C-SiC (3C-polytype silicon carbide), is sensitive to these structural defects. But the second-order Raman features of the structural defects have no distinguished difference. In addition, the carrier concentration within an MP might be higher than that in a SD or a TD, revealing that the carrier traps surrounding the MP are lower than that for the SD or TD. These results offer a simple way for investigating the electrical properties of structural defects in SiC crystals.