Effect of excess vacancy concentration on As and Sb doping in Si

In defect engineering, defects are intentionally introduced in a substrate to modify dopant behaviour. In this work, we used high resolution depth profiling and electrical characterization to analyse As and Sb behaviour in Si substrates with and without excess vacancies. Vacancies were generated by nitrogen or oxygen ion pre-implantation prior to dopant (As or Sb) implantation. Separation by implanted oxygen (SIMOX) samples were also doped and analysed. The results obtained for Si without vacancies and SIMOX were similar in regard to dopant distribution, retention and their electrical characteristics. Vacancy-rich samples show different electrical characteristics and redistribution behaviour during annealing, attributed not just to the presence of vacancies but also to the ion used to create them. In the case of As doping, oxygen pre-implanted samples had a larger retained dose and less As interface accumulation, whereas for Sb doping, nitrogen pre-implanted samples presented a larger retained dose and less Sb interface accumulation. For both dopants, vacancy-rich samples had lower electrically active dopant concentrations, but better thermal stability of the activated dopants when compared with SIMOX and Si.