Electrical activity of extended defects and gettering of metallic impurities in silicon

Electrical activities of slip dislocations and Frank type partial dislocations in Si were investigated using the temperature dependent electron beam induced current technique. It was found that both types of dislocation are recombination active in the temperature range below about 200 K only and inactive in the higher temperature range if they are free from decoration by metallic impurities. From the temperature dependence of the electron beam induced current contrasts, the energy levels of recombination centres on these dislocations were determined to be less than 0.1 ev. They are not accompanied by any deep levels. Debris of defects generated from moving dislocations has deep levels about 0.3-0.4 eV from the band edge even if there is no decoration with metals. Both slip dislocations and Frank partials become recombination active at high temperatures when they getter metallic impurities. The characteristics of impurity gettering by dislocations depend on both the species of impurities and the cooling rate of a Si crystal after contamination. As a result, the recombination activities of dislocations are influenced by a variety of external parameters.