Formation of Oxygen-Related Defects Enhanced by Fluorine in BF2+-Implanted Si Studied by a Monoenergetic Positron Beam

Defects in 25-keV BF2+- or As+-implanted Si specimens were probed by a monoenergetic positron beam. For the As+-implanted specimen, the depth profile of defects was obtained from measurements of Doppler broadening profiles as a function of incident positron energy. The major species of the defects was identified as divacancies. For ion-implanted specimens after annealing treatment, oxygen-related defects were found to be formed. For the BF2+-implanted specimen before annealing treatment, such defects were formed in the subsurface region, where oxygen atoms were implanted by recoil from oxide films. This was attributed to enhanced formation of oxygen-related defects by the presence of F atoms.