Ion-irradiation-induced athermal annealing of helium bubbles in SiC

We have compared the microstructural evolution of helium bubbles under ion irradiation and high temperature annealing. 4H–SiC was irradiated first by 140 keV He ions to a fluence of 1.0 × 1017 cm−2 and then annealed at 1200 K for 30 min. Then, the samples were either irradiated by 2 MeV He ions to a fluence of 3.0 × 1016 cm−2 at room temperature or annealed additionally at 1200 K for 30 min. Before and after 2 MeV He ion irradiation, significant microstructural changes were observed, similar to effects of high temperature annealing. Thus, the study provides evidence of ion-irradiation-induced athermal annealing on defect Ostwald ripening process and bubble evolution. Possible mechanisms are discussed.