The gold-induced crystallization technique has been investigated to achieve poly-Si films on insulators at low temperatures (≤250°C). By annealing (∼250°C) the amorphous Si (a-Si)/Au stacked structures formed on insulating substrates, the positions of Si/Au layers are inverted, and Au/poly-Si stacked structures are obtained. On the other hand, by annealing (>400°C) the structures, mixed layers of c-Si and Au are obtained. These growth phenomena are explained on the basis of the eutectic reaction. This gold-induced layer-exchange growth technique at low-temperatures (∼250°C) is very useful to obtain poly-Si on flexible substrates, which are essential to realize flexible high-speed thin-films transistors and high-efficiency solar cells.