Abstract
4H-SiC and 6H-SiC single crystals were implanted at room temperature with 3-MeV 3He ions at a fluence of 1x1016 cm-2. Analysis of helium migration was carried out with the 3He(d, p)4He nuclear reaction. No clear thermally-activated migration in the end-of-range (EOR) region is found below 1100°C, meaning that helium is strongly trapped probably in helium-vacancy clusters. At 1100°C and above, a fraction of 3He atoms remains trapped in the clusters, but a significant fraction is detrapped into a broad distribution, which is slightly shifted towards the sample surface. Helium detrapping from the EOR region increases with increasing annealing time and temperature. Moreover, the helium content is not conserved, since a significant fraction of 3He atoms is released out of the sample. Helium out-gassing actually increases with increasing annealing time and temperature, up to about 40% at 1150°C. No clear difference is found between the 4H-SiC and 6H-SiC polytypes.