Six-fold helium ion implantation was carried out on nitrogen doped n-type 6H–SiC

epi samples. A box-shaped He-implantation profile and damage region was thus

introduced. Vacancy-type defects in the implanted region were studied by positron

annihilation spectroscopy using a mono-energetic positron beam. The average size

of the vacancy-type defect detected in the as-He-implanted sample was the

divacancy (V2). Thermal annealing had the effect of shrinking the defective region.

Annealing at below 900C had the effect of removing vacancy-type defects in the

defective region. While the annealing temperature was above 900C, the size of the

vacancy-type defects in the defective region increased with annealing temperature.

Upon annealing at 1600C, the defective region reduced to ~100nm and the

vacancy-type defects within the region agglomerated into clusters having an

average size of 14V2.

Vacancy-Type Defects in 6H–Silicon Carbide Induced by He-Implantation: a

Positron Annihilation Spectroscopy Approach. C.Y.Zhu, C.C.Ling, G.Brauer,

W.Anwand, W.Skorupa: Journal of Physics D, 2008, 41[19], 195304