Microstructure, crystallization kinetics and recording characteristics of Si/NiSi bilayer for write-once blu-ray disk

In this study, the Si/NiSi (3 nm/16 nm) bilayer was prepared by sputtering at room temperature to employ as the recording film for write-once blu-ray disk. The thermal properties, crystallization mechanisms and recording characteristics were all investigated in detail. The composition of the NiSi alloy layer was fixed at Ni31Si69. From the result of reflectivity-temperature measurements, it was found that the Si/NiSi bilayer possessed two temperature ranges of reflectivity change, i.e. 156-200 °C and 330-350 °C. Microstructural analysis indicated that the NiSi2 nano-crystalline phase was formed in the as-deposited state. After annealing at 270 °C, the nano-crystallization Si was formed. Upon further increasing the annealing temperature to 500 °C, the crystallinity of Si was enhanced due to its re-crystallization. Dynamic tests reveal that the blu-ray disk with Si/NiSi recording layer has optimum jitter values of 7.5% and 8% at 1 × and 2 × writing speeds, respectively. This indicates that the Si/NiSi bilayer has high potential for the application of write-once blue laser recording media.