Defects properties in plastically deformed silicon studied by positron lifetime measurements
Positron lifetime spectra have been measured in float-zone silicon plastically deformed at different temperatures. The temperature dependences of lifetime spectra were measured for all as-deformed and annealing samples. The experimental results indicate that there are three kinds of defects (vacancy clusters, dislocation-bound vacancies and undisturbed dislocations) induced by deformation. The size and concentration of vacancy-clusters depend on the strain temperature in the case of similar strains and strain rates. Dislocation-bound vacancies were quite stable. They could not be annealed out thoroughly after thermal treatment at 1300C. At sample temperatures below 120 K, regular dislocation segments have a significant influence on positron trapping. Their effect as positron shallow traps influences significantly the course of the measured average positron lifetime.
plastic deformation silicon dislocation point defects positron annihilation