Positron annihilation in ion implanted silicon layers

Angular distribution study of positron annihilation photons was used to investigate monocrystalline (100) samples of the hole silicon doped with boron ions with 50 keV energy and dose 3.10x1015cm-2 (p-Si(B)-(100). Triple layer model (for annihilation in the monocrystalline substrate, in amorphous layer and at the sample surface) was used for an analysis of the results. It is concluded that the probability of positron annihilation in the amorphous layer and at the surface cannot be derived only from positron diffusion without the consideration of the electric field effect. The results obtained on monosilicon, silicon doped with boron and phosphorus at various dopant concentrations and also on amorphous silicon demonstrated that the potential of the positron interaction with the near-surface layers of the doped sample has the form of a potential well in the amorphous layer at a distance of about a mean positron projective path from the surface. The potential well depth is also estimated