A mass transfer model has been built up for metal ion implantation into Al target at
elevated temperature, based on the transport of ions in matter and the radiation enhanced diffusion
theory, which is applicable to calculate the concentration--depth profiles of the implanted species. With
the model, the ion implantation process at elevated temperature was simulated by the Monte Carlo
method and the local saturation behavior in the crystal target simulated using a maximum allowed
atomic fraction. Moreover, the diffusion process was described with the radiation enhanced diffusion
theory. Thus the concentration--depth profiles of the implanted species were determined from the dif-
fusion equations for the implanted species and nonequilibrium vacancies, and the radiation enhanced
diffusion coefficient was obtained by taking into account the linear annealing defects. The nonequi-
librium vacancy source function and the surface sputtering effects were introduced in the diffusion
equations. The calculated concentration--depth profiles of Cr ions implanted into Al are consistent with
the experimental ones at the target temperatures of 250, 400 and 510℃, with an ion energy of 140
keV and an implanted dose of 2×10~(17) ions cm~(-2).