The dependence of the Doppler-broadened annihilation linewidth parameter upon the implanted ion dose was measured by using a controlled-energy positron beam and n-type float-zone (100)-oriented material which had been implanted with 120keV Ge+, 400keV O+, 200keV He+ or 450keV H+ ions. The linewidth parameter increased with dose for all of the ions; thus indicating the presence of vacancy-type defects. It was found that the maximum linewidth parameter values for the various implants could be normalized to a single well-defined distribution by using predicted values of the vacancy concentration. This implied that vacancy-type defects which resulted from the implantation were always similar in both structure and interstitial recombination rate. The data for He+ did not lie exactly on the above universal distribution, and this was attributed to defect passivation by the implanted He.

The Equivalence of Vacancy-Type Damage in Ion-Implanted Si Seen by Positron Annihilation Spectroscopy A.P.Knights, F.Malik, P.G.Coleman: Applied Physics Letters, 1999, 75[4], 466-8