Defects in MeV Si-implanted Si probed with positrons

Abstract

Vacancy‐type defects produced by implantation of MeV doses of Si ions (10¹¹–10¹⁵ atoms/cm²) at room temperature have been probed using depth‐resolved positron annihilation spectroscopy. The defect (divacancy) concentration increases linearly with dose for low doses (12 Si/cm²). In situ isochronal annealing was followed for oxygen‐containing Si (10 ppm) and oxygen‐‘‘free’’ Si implanted to doses (5×10¹² and 5×10¹⁴ Si/cm²). Two main annealing stages were observed at the same temperatures in the studied samples in spite of significant differences in doses and oxygen content. In the first stage (∼200 °C) a significant fraction of divacancies was observed to form large vacancy clusters. These clusters were removed in the second stage (∼675 °C) after which the oxygen‐free samples returned to pre‐irradiation conditions, whereas oxygen‐defect complexes were formed in the oxygen‐containing samples.