We use molecular dynamics techniques to study the ion beam induced enhancement in the growth rate of microcrystals embedded in an amorphous silicon matrix. The influence of the ion beam on the amorphous‐to‐crystal transformation was separated into thermal annealing effects and defect production effects. Thermal effects were simulated by heating the sample above the amorphous melting point, and damage induced effects by introducing several low energy recoils in the amorphous matrix directed at the crystalline grain. In both cases, the growth rate of the microcrystals is enhanced several orders of magnitude with respect to the pure thermal process, in agreement with experimental results. The dynamics of the crystallization process and the defect structures generated during the growth were analyzed and will be discussed. ©1996 American Institute of Physics.