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- Polycrystalline SiC samples were first implanted with 200 keV selenium (Se) ions at room temperature (RT) to a fluence of 1 ×1016 cm2. Thereafter, some of the pre-implanted SiC samples were separately implanted with helium (He) ions of 17 keV to a fluence of 1 ×1017 cm2 at RT and 500 ◦C. The samples were then annealed in a vacuum at 1000 ◦C for 5 h. Raman spectroscopy and transmission electron microscopy (TEM) were used to study the influence of Se and He co-implantation and annealing on the microstructure of SiC. Rutherford backscattering spectrometry (RBS) was used to study the migration behavior of Se in SiC before and after co-implantation and annealing. Implantation of Se at RT amorphized the SiC near the surface implanted region. Co-implantation at RT created a high portion of free carbon atoms in the damaged region accompanied by the formation of He nano- bubbles, while co-implantation at 500 ◦C led to some recrystallization of initially amorphous SiC and formation of larger He bubbles. Annealing at 1000 ◦C caused some recrystallization in both as-implanted (SiC implanted with Se only) and co-implanted samples. However, the recrystallization was accompanied by the formation of graphite crystals (with an average size of 10 nm) in the samples co-implanted at RT. This indicates that co- implantation at RT induces more detrimental effects on the physical integrity of SiC. RBS results showed no change in Se distribution in SiC after subsequent implantation with He ions at RT and 500 ◦C. However, annealing at 1000 ◦C caused the Se atoms to migrate towards the bulk of SiC in the co-implanted samples, while no significant migration of Se atoms was observed in the as-implanted samples (SiC implanted with Se only) annealed under the same conditions. This suggests that He assisted Se migration in SiC.
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