Positron annihilations associated with defects in plastically deformed Si

Deformation-induced defects in Si have been studied using positron lifetime measurement. Two lifetime components, 285 ps and 544 ps, which were assigned to dislocation-related defects and vacancy clusters, respectively, were observed. Through annealing experiments, the dislocation-related component was found to consist of two more components: one annihilated after the annealing at around 900°C and the other remaining even at 1100°C. These were attributed to vacancy like parts on dislocations and to dislocations themselves, respectively. Positron trapping rate due to dislocations increased upon cooling and saturated below 80 K. It was approximately proportional to the inverse of the temperature (approx.T-1) in the temperature range between 100 and 300 K. These features were interpreted in terms of shallow levels originating from strain fields around dislocations and the one-dimensionality of dislocations.