The nanocomposite thin film applied to high-density write-once optical data storage

Abstract

This work demonstrates the feasibility of producing composite thin films containing nano-scale recording particles for highdensity optical data storage. The nanocomposite recording layers were found to exhibit an ultrafast transition rate and a unique phase transition temperature compared with the bilayer recording systems. For type I disk samples containing a nanocomposite recording layer and a Ag reflection layer, modulations higher than 0.8 and 0.5 could be achieved when I IT and 4T signals were respectively written into the disk samples using a blue-laser dynamic tester. As for type 11 disk samples containing a sole nanocomposite recording layer, modulations better than 0.8 and 0.6 were obtained. Transmission electron microscopy (TEM) characterization attributed the main signal recording mechanism to the coalescence and coarsening of nano-recording particles, which, in turn, implies a sufficient reflectivity difference for signal readout. The reactions and/or redistribution of elements involved in the layer structure of optical disks also contributed to the signal recording. The nanocomposite recording layer provides various advantages including a fast phase transition rate, initialization-free, disk structure simplification, and a sputtering-compatible fabrication process and thus, promising applications to next-generation write-once optical data storage are expected.