Experimental test of kinetic theories for heterogeneous freezing in silicon.

The crystallization rate of liquid silicon has been measured during epitaxial explosive crystallization of amorphous silicon. The measurements, together with numerical temperature calculations indicate that freezing in silicon saturates at 15.8 m/s for large undercooling (>130 K) below the equilibrium melting temperature. These data, as well as a variety of experimental results of other investigators, are used to test two models describing the kinetics of heterogeneous freezing. A transition-state theory in which the phase transformations are assumed to go through an intermediate state at a rate limited by the sound velocity is not consistent with the data