Enhancement of depth sensitivity in slow positron implantation spectroscopy of Si

Information gained by non-destructive slow positron implantation spectroscopy on the depth distribution of open-volume defects created by ion implantation in Si is limited. In particular, determination of the shape of defect tails is hampered by the dominance of the positron response to defects in the peaked subsurface distribution and the unavoidable decrease in depth resolution as the incident positron energy increases and the positron implantation profile broadens. Enhanced depth resolution is achieved by combining standard positron-beam-based Doppler broadening spectroscopy with controlled removal of thin layers of the implanted sample by anodic oxidation and etching. The technique is described in detail and examples of its capabilities are shown using both simulated and experimental data.