Direct evidence, obtained by positron annihilation spectroscopy, was found for the complexing of F with vacancies in Si. Both float-zone and Czochralski Si wafers were implanted with 30keV F ions to a fluence of 2 x 1014/cm2, and studied in the as-implanted condition or after annealing (650C, 600s or 0.5h). The so-called 2-detector background reduction technique for positron annihilation was applied. The spectra revealed a significant concentration of F-vacancy complexes after annealing, for both Czochralski and float-zone material, thus supporting the results of computer simulations of the implantation and annealing process.

Observation of Fluorine-Vacancy Complexes in Silicon. P.J.Simpson, Z.Jenei, P.Asoka-Kumar, R.R.Robison, M.E.Law: Applied Physics Letters, 2004, 85[9], 1538-40