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 i n Czochralski-grown Si were studied by means of positron lifetime meas urements. Several annealing processes were identified from a compariso n with previous EPR results. The activation energies were also determi ned from an analysis of isothermal annealing. The results are summariz ed as follows. Divacancies (V(2)s) disappear around 250 degrees C to f orm divacancy+oxygen (V2O) complexes. The activation energy for the an nealing of divacancies is determined to be 1.30 eV. The V2O complexes disappear at around 400 degrees C to form trivacancy+oxygen (V3O) and divacancy+dioxygen (V2O2) complexes. The activation energy for the ann ealing of V2O complexes is determined to be 2.14 eV. The V3O and V2O2 complexes disappear at around 440 degrees C to form trivacancy-dioxyge n (V3O2) complexes. The activation energy for the annealings of these defects is determined to be 2.23 eV. The V3O2 complexes disappear at a round 475 degrees C. The activation energy is determined to be 2.56 eV . The annealing processes of divacancies, vacancy+oxygen (VO) and vaca ncy+dioxygen (VO2) complexes were also examined from measurement of th eir infrared absorption. Temperature dependent changes of the absorpti on coefficient due to divacancies are in good agreement with temperatu re dependent changes of the positron trapping rate due to divacancies. Positron trapping at VO and VO2 complexes was not detected, in contra st to the measurement of optical absorption.