Figure 1

a S parameter as a function of the positron implantation energy in the SOI sample. Error bar is shown for one point only. b Dashed lines represent the fractions of positrons implanted into the oxide (blue) and the silicon substrate (red), calculated according to Ref. [11]. The continue and dash-doted lines represent the fractions of positrons that annihilate after diffusion in the oxide (blue), at the buried interface (green) and into the substrate (red). Surface effects are not visible in the picture (important only at low energies). The upper scale gives the mean positron implantation depth calculated according to Eq. 1