Mesoscale modelling of the yield point properties of silicon crystals

The yield point properties that characterize silicon crystals in the temperature domain where Peierls forces govern the dislocation mobility have been investigated in easy glide conditions with the help of a three-dimensional mesoscopic simulation of dislocation dynamics. The influence of temperature, applied strain rate and initial dislocation microstructure, the latter consisting of a random initial distribution of dislocation sources, were examined in detail and globally found in fair agreement with the available experimental results. A critical examination of a well-known model by Alexander and Haasen has been performed, leading to a discussion and reformulation of the law accounting for the multiplication rate of dislocations. The present lack of knowledge on the mechanisms by which new dislocation sources are formed during the plastic deformation of silicon crystals is emphasized. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.