The depth distributions of defects in 50keV As+-implanted samples, with a cap layer of SiO2 or SiN, were deduced from measurements of the Doppler broadening spectra of annihilation radiation and the lifetime spectra of positrons. Before annealing, the main defects below the amorphous region were divacancies. Upon annealing at 800C, O-related defects were introduced into the sub-surface region (20 to 40nm). These defects were identified as being O micro-clusters. The positrons were trapped by open spaces adjacent to the clusters, and the size of the spaces was estimated to be close to that of monovacancies. The O-related defects were removed by rapid thermal annealing (1050C, 10s). It was noted that As+ implantation through a SiN film suppressed the introduction of recoiled O atoms. As a result, the concentration of O-related defects decreased.

Oxygen-Related Defects Introduced by As+-Implantation through Cap Layers in Si Probed by Mono-Energetic Positron Beams. A.Uedono, M.Muramatsu, T.Ubukata, H.Tanino, S.Tanigawa, A.Nakano, H.Yamamoto, R.Suzuki, T.Ohdaira, T.Mikado: Japanese Journal of Applied Physics - 1, 2000, 39[11], 6126-9