Defects in 25keV BF2+-implanted or 25keV As+-implanted specimens were studied by using a mono-energetic positron beam. In the case of the As+-implanted material, the depth profiles of defects were deduced from measurements of the Doppler-broadening profiles as a function of the incident positron energy. The main defects were found to be di-vacancies. In ion-implanted specimens after annealing, O-related defects were formed. In the case of BF2+-implanted specimens before annealing, such defects formed in the sub-surface region; where O atoms were implanted by recoil from oxide films. This was attributed to the enhanced formation of O-related defects by the presence of F atoms.

A.Uedono, T.Moriya, T.Kawano, S.Tanigawa, R.Nagai, K.Umeda: Japanese Journal of Applied Physics, 1995, 34[1-12A], 6293-7