A study was made of p+-n junctions which had been produced in n-type epitaxial wafers having O and C contents of less than 1015/cm3. The samples were implanted with 2.5MeV He ions to fluences of between 109 and 1012/cm2 at room temperature. The junctions were reverse-biased at -30V in order to keep the entire ion-damage profile within the depletion layer. It was found that the leakage current increased monotonically during implantation. When the beam was turned off, it decreased by a factor of about 2 during times of up to 24h. Deep-level transient spectroscopic measurements showed that the main contributors to the leakage current were the deep levels which were introduced into the band-gap by P vacancy and divacancy complexes. The leakage current reduction at beam turn-off was linked to the recombination of vacancy-type complexes by residual free interstitials. When the ion flux was increased at a given fluence, an initial faster transient which lasted for up to about 1000s was observed and was attributed to the annihilation of residual free vacancies. Diffusivities of 1.5 x 10-15 and 3.0 x 10-13cm2/s were deduced for interstitials and vacancies, respectively.

Room-temperature diffusivity of self-interstitials and vacancies in ion-implanted Si S.Coffa, S.Libertino: Applied Physics Letters, 1998, 73[23], 3369-71