Pre-cavities defect distribution in He implanted silicon studied by slow positron beam

Several techniques were applied to study distributions of point defects created after He implantation in Si at an energy of 20 keV. The evolution of the defect distributions as a function of isocronal thermal anneling was studied in the 150-900 degrees C temperature range. In particular Doppler-broadening measurements with a slow positron beam were performed to gain information on open volume defects precursors of the cavities that are formed in He implanted silicon after thermal treatment. Profiles of displaced Si atoms, He, and vacancies are presented for the meaningful thermal treatments, and discussed.