Low-temperature crystallization of hydrogenated amorphous silicon induced by nickel silicide formation

We have investigated the silicidation process of the Ni/a-Si:H system on a fused silica substrate mainly by in situ electric resistance measurement. A rise of the resistance is observed in the temperature range of 480–510°C of the resistance curve at a heating rate of 2 K/min. The results of the RBS measurements and the XRD measurements show that the rise of the resistance originates from the diffusion of Ni from the NiSi 2 layer to a-Si:H film, and that the a-Si:H crystallizes during the diffusion. Noting that the crystallization temperature of a-Si:H film is higher than 700°C, the present crystallization occurs at a much lower temperature. It is suggested that this low-temperature crystallization is induced by heterogeneous nucleation, where the NiSi 2 becomes the nucleus for Si crystallization.