Effect of Xe ion (167 MeV) irradiation on polycrystalline SiC implanted with Kr and Xe at room temperature

The effect of swift heavy ion (Xe 167 MeV) irradiation on polycrystalline SiC individually \nimplanted with 360 keV Kr and Xe ions at room temperature to fluences of 2×1016 cm-2 and \n1×1016 cm-2 respectively, was investigated using transmission electron microscopy (TEM), \nRaman spectroscopy and Rutherford backscattering spectrometry (RBS). Implanted \nspecimens were each irradiated with 167 MeV Xe+26 ions to a fluence of 8.3×1014 cm-2 at \nroom temperature. It was observed that implantation of 360 keV Kr and Xe ions individually \nat room temperature amorphized the SiC from the surface up to a depth of 186 and 219 nm \nrespectively. Swift heavy ion (SHI) irradiation reduced the amorphous layer by about 27 nm \nand 30 nm for the Kr and Xe samples respectively. Interestingly, the reduction in the \namorphous layer was accompanied by the appearance of randomly oriented nanocrystals in \nthe former amorphous layers after SHI irradiation in both samples. Previously, no similar \nnanocrystals were observed after SHI irradiations at electron stopping powers of 33 keV/nm \nand 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. \nRaman results also indicated some annealing of radiation damage after swift heavy ion \nirradiation and the subsequent formation of small SiC crystals in the amorphous layers. No \ndiffusion of implanted Kr and Xe was observed after swift heavy ion irradiation.