Dynamic crystallization behavior of phase change optical recording in erasing process

Phase change recording is an emerging technology for achieving removable high density data storage compatible with CD or DVD ROM. The data transfer rate (DTR) is one of the most important parameters for PC optical recording disks. DTR is primarily limited by the crystallization speed of the amorphous marks in the recording layer. The amorphous marks cannot be completely erased when the crystallization speed is not fast enough to match the linear velocity of the laser light spot with respect to the disk. This would cause distortions in the shape of the overwritten marks, and results in a high level of noise. Therefore the re-crystallization behavior of the phase change layer is fundamental to phase change recording technology. AgInSbTe and GeSbTe are two main phase change materials used in current phase change optical disks. The complete erasing time (CET) of the former one increases strongly with an increase of the size of the written mark, and therefore is called a growth-driven material. The CET of the latter increases only slightly with the increase of the size of the written mark, and therefore is called a nucleation-driven material. In order to achieve high DTR, we must study the dynamic erasing behavior of phase change optical disks. This article addresses how marks are erased in rewritable phase change optical disks.