Raman scattering of neutron irradiated 6H-SiC

Confocal micro-Raman spectroscopy was preformed to investigate the structural damage of SiC neutron irradiated with the fluences of 1.72×1019 and 1.67×1020 n/cm2. In addition to characteristic peaks, several additional signals related to Si–Si, Si–C, and C–C vibration modes were monitored. The vibration mode associated with CSiV C complexes was identified to be the unambiguous peak at 575 cm−1 which appears initially in the sample post-irradiation annealed at 800 °C. The defect-induced phonon confinement effect results in an asymmetric broadening with a low-frequency tail of the optical phonon peaks. The sigmoidal thermal recovery behavior of the optical phonon frequencies indicates that the reduction of FLO0/6–FTO2/6 splitting originates mainly from the isolated vacancies and interstitials.

► Neutron-irradiation induced local vibration modes.
► Thermal evolution of the modes.
► Defect-induced phonon confinement effect.
► The origin of the reduction of FLO0/6–FTO2/6 splitting.