In 4H–SiC, damage created by He implantation at high fluence (5 x 1016/cm2) and high energy (1.6MeV) was studied by using different techniques of electron microscopy all along the ion path. Around the end-of-range, conventional transmission electron microscopy was used to observe the fine microstructure of defects in the as-implanted and 1500C annealed samples. No bubbles were found in the as-implanted sample while numerous cavities with different shape, size and density were present after annealing. The amorphous-crystalline transition region was checked by high-resolution transmission electron microscopy. The strain profile, determined by using the large angle convergent beam electron diffraction, showed a strong correlation with the nuclear stopping curve given by SRIM simulation. The dilatation of the c-axis measured all along the ion path was in agreement with the value of the observed swelling. Relaxation volumes for interstitial and vacancy did not cancel. After annealing the cavity parameters were found to be dependent on both the He density and the as-implanted microstructure.

Transmission Electron Microscopy Investigations of Damage Induced by High-Energy Helium Implantation in 4H–SiC. M.F.Beaufort, F.Pailloux, A.Declémy, J.F.Barbot: Journal of Applied Physics, 2003, 94[11], 7116-20