Defects in 4H-SiC Induced by High Energy Helium Implantation

1.6 MeV He + ions were implanted at room temperature into (0001) 4H-SiC at a dose of 1×10 17 cm −2 and then annealed at 1500°C for 30 min. Small bubbles are readily observed in the as-implanted sample but also an amorphous layer. After a 1500°C annealing, recrystallization of the amorphous state occurs and large bubbles or cavities are observed. However their shape strongly depends of their location inside the buried layer. The recrystallization consists of polytypisme, 4H-SiC growth along the c-direction from the substrate, columnar 4H-SiC and epitaxial growth of 3C-SiC.