Understanding the migration of metal clusters within amorphous matrices and crystallization dynamics is fundamental to tailoring interface reactions and designing material functionalities. Despite extensive advances in metal-induced crystallization, the atomistic dynamic pathways and microscopic mechanisms of metal long-range diffusion on disordered matter remain elusive. Here, we employ atomic-resolution in situ heating transmission electron microscopy, integrated with density functional theory calculations, to systematically investigate the Au cluster long-range diffusion on amorphous silicon (a-Si) and the simultaneous resulting crystallization mechanism at the atomic scale. Amorphous Au clusters follow Arrhenius-type diffusion kinetics with an activation energy barrier of approximately 0.69 eV, notably without the formation of any intermediate metal silicide. Our dynamic observations reveal two synergistic diffusion modes: linear homogeneous diffusion and nonlinear aggregation-spreading, fundamentally driven by the higher diffusion barrier on the amorphous surface compared to its crystalline counterpart. These results offer atomic-scale evidence for Au surface diffusion and its role in mediating crystallization, thereby providing a pathway for exploring surface diffusion dynamics at amorphous-amorphous/crystalline interfaces.
李宗耀 et al. (Wed,) studied this question.