Vacancy-type defects in 6H-silicon carbide induced by He-implantation: A positron annihilation spectroscopy approach

Abstract

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 monoenergetic positron beam. The average size of the vacancy-type defect detected in the as-He-implanted sample was the divacancy (V 2). Thermal annealing had the effect of shrinking the defective region. Annealing at temperatures lower than 900 °C had the effect of removing vacancy-type defects in the defective region. While the annealing temperature is above 900 °C, the size of the vacancy-type defects in the defective region increased with annealing temperature. At the annealing temperature of 1600 °C, the defective region reduced to ∼100 nm and the vacancy-type defects within the region agglomerated to clusters having an average size of 14 V 2. © 2008 IOP Publishing Ltd.