Investigation of the damage behavior in CVD SiC irradiated with 70Â keV He ions by NEXAFS, Raman and TEM

Chemical vapor deposited (CVD) SiC was irradiated with 70 keV He ions at room temperature. The damage behavior was investigated by near edge X-ray absorption fine structure (NEXAFS) spectroscopy, Raman spectroscopy and transmission electron microscopy (TEM). NEXAFS spectra at the Si K-edge display the obvious decrease in intensity of crystalline peaks and near disappearance of the peak at 1852 eV, suggesting an increase in crystalline disorder resulting from an increased number of Si vacancies caused by irradiation. Raman spectra show the decomposition of crystalline Si-C bonds and the formation of homonuclear (Si-Si and CC) bonds during irradiation. TEM results show the transition from slight disorder to full amorphization with increasing dose. The dose to amorphization (DTA) is estimated to be about 1 dpa. It is also found that high density of stacking faults in CVD SiC may contribute to the enhancement of amorphization resistance compared to single crystal β-SiC.