Recombination activity of contaminated dislocations in silicon: A model describing electron-beam-induced current contrast behavior

Abstract

Existing experimental data give many evidences that the recombination rate of minority charge carriers at dislocations in silicon depends strongly on dislocation decoration by transition metal impurities. Here, we present a model that allows a quantitative description of the recombination of minority carriers at decorated dislocations. It assumes that shallow dislocation bands, induced by the strain field, and deep electronic levels, caused by impurity atoms, which have segregated at the dislocation, or by core defects, can exchange electrons and holes. As a consequence, the recombination of carriers captured at dislocation bands can be drastically enhanced by the presence of even small concentrations of impurity atoms at the dislocation core. The model allows us not only to explain experimentally observed dependences of the recombination rate on temperature and excitation level, but also to estimate the concentration of deep level impurities at dislocations.