Impact of supercooled liquid structures on the crystallization processes of amorphous Ge

The crystallization processes of amorphous Ge as well as the atomistic structures of the growth front were examined by molecular-dynamics simulations. An amorphous Ge network was annealed in a thermal bath with a temperature gradient. Crystallization proceeded via the supercooled liquid, and changed from random nanocrystallization to large-oriented grain growth. The resultant structures qualitatively reproduced the explosive crystallization observed with pulsed-laser irradiation and flash lamp annealing. The supercooled liquid was found to transform from a tetrahedral liquid to a more highly-coordinated liquid with increasing temperature, which was attributed to the change in growth mode.