Investigation of irradiation effects induced by self-ion in 6H-SiC combining RBS/C, Raman and XRD

Single crystals of 6H-SiC were irradiated at room temperature and 670 K with 4 MeV C ions at two fluences: 10 ¹⁵ and 10 ¹⁶ cm ^-2 (0.16 and 1.6 dpa at the damage peak). Damage accumulation was studied by a combination of X-ray diffraction (XRD), Raman spectroscopy and Rutherford backscattering spectrometry in channelling geometry (RBS/C) along the [0 0 0 1] direction. The irradiated layer is found to be composed of a low damage region up to ∼1.5 μm followed by a region where the disorder level is higher, consistent with SRIM predictions. At room temperature and low fluence, typically 10 ¹⁵ cm ^-2, the strain depth profile follows the dpa depth distribution (with a maximum value of ∼2%). The disorder is most likely due to small defect clusters. When increasing the fluence up to 10 ¹⁶ cm ^-2, a buried amorphous layer forms, as indicated by e.g. Raman results where the Si-C bands become broader or even disappear. At a higher irradiation temperature of 670 K, amorphization is not observed at the same fluence, revealing a dynamic annealing process. However, results tend to suggest that the irradiated layer is highly heterogeneous and composed of different types of defects.