Depth profiling of defects in ion-implanted Ni and Fe by positron annihilation measurements

Pure Ni and Fe samples were irradiated with 150 keV Ar ions at room temperature, 300 and 500 °C to introduce defects near the surface. The irradiated samples were characterized by energy-variable slow-positron beams with Doppler broadening and positron lifetime measurements to investigate defect profiles. The irradiation-induced defects were detected at regions much deeper than ion projected ranges for all the temperatures. The origin of such defects beyond the projected ranges was discussed in terms of vacancy migration, ion channeling, surface contamination and depth-scale error. Among these effects, the ion channeling may account for the obtained results.