Superlattice-like structure for phase change optical recording

In order to increase the crystallization speed and data transfer rate (DTR), a superlattice-like structure (SLL) was applied to the recording layer of phase change optical disks. Unlike the conventional phase change layer, the recording layer with the SLL structure consisted of alternating thin layers of two different phase change materials, i.e., GeTe and Sb2Te3. Although neither GeTe nor Sb2Te3 could be used as a phase change layer material for practical applications, present experimental results revealed that the phase change optical disk with the SLL structure demonstrated an excellent recording property that could meet practical recording requirements. X-ray photoelectron spectroscopy was employed to confirm that the SLL structure could be preserved after many times of melting and quenching. Dynamic properties of the optical recording disk with the SLL structure were investigated with a 1 T pulse duration of 8 ns and a constant linear velocity of 19 m/s. A clear eye pattern was observed. The carrier-to-noise ratio was about 58 dB and a DTR of 47 Mbit/s was achieved. The DTR would be as high as 140 Mbit/s if the blue light is used. It has been proven that the SLL structure is a useful means to increase the DTR of phase change optical recording disks.