Microstructures and recording mechanism of Mo/Si bilayer applied for write-once blue laser optical recording

Mo/Si bilayer thin films were grown by magnetron sputtering and applied to write-once blu-ray disc (BD-R). The microstructures and optical storage properties of Mo/Si bilayer were investigated. From the temperature dependence of reflectivity measurement, it was revealed that a phase change occurred in the range of 255-425°C. Transmission electron microscopy analysis showed that the as-deposited film possessed Mo polycrystalline phase. The hexagonal MoSi₂ and cubic Mo₃Si phases appeared after annealing at 300 and 450°C, respectively. By measuring the optical reflectivity at a wavelength of 405 nm, the optical contrast of Mo/Si bilayer between as-deposited and 450°C-annealed states was evaluated to 25.8%. The optimum jitter value of 6.8% was obtained at 10.65 mW for 4× recording speed. The dynamic tests show that the Mo/Si bilayer has high potential in BD-R applications.