MICROSEGREGATION FAR FROM EQUILIBRIUM

Monte Carlo computer simulations of the crystallization of a two compo nent mixture have been performed for crystallization conditions which are far from equilibrium in order to determine the dependence of the d istribution coefficient (k-value) on the growth conditions. The simula tions were based on the Ising model for a two component mixture, and t he thermodynamic properties of Si doped with Bi were used as a model a lloy system. At rapid crystallization rates, the k-value in the simula tions differs significantly from the equilibrium value, and depends on the square of the growth rate and inversely on the diffusion coeffici ent in the liquid. The k-value in the simulations is found to be stron gly orientation dependent, in accordance with experimental results on silicon. The simulation results are compared with experimental results which have been reported in the literature for the dependence of the k-value on growth rate in laser melted silicon which has been ion impl anted with bismuth.