Raman spectroscopy study of heavy-ion-irradiated $\alpha$-SiC

Raman spectroscopy was used to investigate the structure of ion-irradiated α-SiC single crystals at room temperature and 400 °C. Irradiations induce a decrease of the Raman line intensities related to crystalline SiC, the appearance of several new Si–C vibration bands attributed to the breakdown of the Raman selection rules, and the formation of homonuclear bonds Si–Si and C–C within the SiC network. For low doses, the overall sp3 bond structure and the chemical order may be almost completely conserved. By contrast, the amorphous state shows a strong randomization of the Si–Si, Si–C and C–C bonds. The relative Raman intensity decreases exponentially versus increasing dose due to the absorption of the irradiated layer. The total disorder follows a sigmoidal curve, which is well fitted by the direct impact/defect stimulated model. The chemical disorder expressed as the ratio of C–C bonds to Si–C bonds increases exponentially versus the dose. A clear correlation is established between the total disorder and the chemical disorder. The increase of temperature allows the stabilization of a disordered/distorted state and a limitation of damage accumulation owing to the enhancement of the dynamic annealing