Abstract:
The effect of swift heavy ion (Xe 167 MeV) irradiation on polycrystalline SiC individually
implanted with 360 keV Kr and Xe ions at room temperature to fluences of 2×1016 cm-2 and
1×1016 cm-2 respectively, was investigated using transmission electron microscopy (TEM),
Raman spectroscopy and Rutherford backscattering spectrometry (RBS). Implanted
specimens were each irradiated with 167 MeV Xe+26 ions to a fluence of 8.3×1014 cm-2 at
room temperature. It was observed that implantation of 360 keV Kr and Xe ions individually
at room temperature amorphized the SiC from the surface up to a depth of 186 and 219 nm
respectively. Swift heavy ion (SHI) irradiation reduced the amorphous layer by about 27 nm
and 30 nm for the Kr and Xe samples respectively. Interestingly, the reduction in the
amorphous layer was accompanied by the appearance of randomly oriented nanocrystals in
the former amorphous layers after SHI irradiation in both samples. Previously, no similar
nanocrystals were observed after SHI irradiations at electron stopping powers of 33 keV/nm
and 20 keV/nm to fluences below 1014 cm-2. Therefore, our results suggest a fluence threshold for the formation of nanocrystals in the initial amorphous SiC after SHI irradiation.
Raman results also indicated some annealing of radiation damage after swift heavy ion
irradiation and the subsequent formation of small SiC crystals in the amorphous layers. No
diffusion of implanted Kr and Xe was observed after swift heavy ion irradiation.
