An annealing study of defects induced by electron irradiation of Czochralski-grown Si using a positron lifetime technique

Annealing processes of defects induced by 3 MeV electron irradiation in Czochralski-grown Si were studied by means of positron lifetime measurements. Several annealing processes were identified from a comparison with previous EPR results. The activation energies were also determined from an analysis of isothermal annealing. The results are summarized as follows. Divacancies (V2s) disappear around 250°C to form divacancy + oxygen (V2O) complexes. The activation energy for the annealing of divacancies is determined to be 1.30 eV. The V2O complexes disappear at around 400°C to form trivacancy + oxygen (V3O) and divacancy + dioxygen (V2O2) complexes. The activation energy for the annealing of V2O complexes is determined to be 2.14 eV. The V3O and V2O2 complexes disappear at around 440°C to form trivacancy-dioxygen (V3O2) complexes. The activation energy for the annealings of these defects is determined to be 2.23 eV. The V3O2 complexes disappear at around 475°C. The activation energy is determined to be 2.56 eV. The annealing processes of divacancies, vacancy + oxygen (VO) and vacancy + dioxygen (VO2) complexes were also examined from measurement of their infrared absorption. Temperature dependent changes of the absorption coefficient due to divacancies are in good agreement with temperature dependent changes of the positron trapping rate due to divacancies. Positron trapping at VO and VO2 complexes was not detected, in contrast to the measurement of optical absorption.