Transient reactions among irradiation defects, dopants, impurities and carriers in pulse-neutron-irradiated Si were modelled while taking account of clustering of the primary defects in recoil cascades. Continuum equations describing the diffusion, field drift and reactions of relevant species were solved numerically for a sub-micrometer spherical volume, within which the starting radial distributions of defects could be varied in accord with the degree of clustering. The radial profiles corresponding to neutron irradiation were chosen via pair-correlation-function analyses of vacancy and interstitial distributions obtained from a binary-collision code, using a spectrum of primary recoil energies computed for a fast-burst fission reactor. Model predictions of transient behavior were compared with various experimental results from irradiated bulk Si, solar cells, and bipolar-junction transistors. The influence of defect clustering during neutron bombardment was further distinguished by contrasting it with electron irradiation, where the primary point defects were more uniformly dispersed.

Model of Defect Reactions and the Influence of Clustering in Pulse-Neutron-Irradiated Si. S.M.Myers, P.J.Cooper, W.R.Wampler: Journal of Applied Physics, 2008, 104[4], 044507