Specific features of recombination on complex radiative defects in fast neutron irradiated silicon

A model of a spherical cluster with double vacancies is considered for silicon irradiated by fast neutrons. It is supposed that the number of double vacancies as a function of energy of the primarily-shifted atom obeys the Lindhart theory, and the average radius of the cluster obeys the Zigmund and Sunders theory. Continuity and Poisson equations are numerically solved for an inhomogeneous crystals with clusters. Good agreement is established for the p-type silicon and for n-type low-resistance silicon. The dependence of damage on energy and neutron transfer and also the influence of inaccuracy in determining the parameters of defects and idealizing of the real shape of cluster have been analyzed. It is shown that the defect levels inside the cluster may be considered as isolated, neglecting multivalence of double vacancies. The results presented provide evidence of the fact that the model of clusters of defects constructed on a real physical ground is able to explain both qualitatively and quantitatively the experimental results on the fast neutron irradiation of silicon