Depth profile of vacancy-type defects in B+-implanted Si with a SiO2 overlayer by a variable-energy positron beam

A variable-energy positron beam technique has been used to probe the vacancy-type defects in Si with a 43-nm-thick SiO2 layer induced by B+ implantation with the energy of 80 keV. From the measurements of line shape parameters as a function of incident positron energy, it was found that defects in the Si substrate are distributed in a parabolic form with the average depth shallower by 27% than the projected range of B+ ions for the specimen with a dose of 5×1012 B/cm2 and that defects are accumulated in large quantities at the SiO2 /Si interface for the specimen with higher doses.