Amorphous FeSi2 thin films of stoichiometric composition were deposited on an n-type (1 0 0) Si substrates by laser ablation. In order to investigate the formation and growth processes of the beta-FeSi2 phase, both isothermal annealing and isochronal annealing have been carried out. The results show that the metastable FeSi phase and the beta-FeSi2 phase are dominant at annealing temperatures of T-a less than or equal to 700degreesC and T-a greater than or equal to 700degreesC, respectively. The growth of the beta-FeSi2 phase is achieved under an annealing condition of T-a greater than or equal to 800degreesC and an annealing time of t(a) greater than or equal to 60 min. Moreover, it has been shown that the dominant growth process of the (1 1 0) beta-FeSi2 phase following the nucleation is due to the diffusion of Fe and/or Si induced by the decomposition of the metastable FeSi phase, where the activation energy is estimated to be 0.34 eV for the diffusion in the amorphous FeSi2 matrix. (C) 2002 Elsevier Science B.V. All rights reserved.