High-Density Recording on a Phase-Change Optical Disk with Suppression of Material Flow and Recording-Mark Shape-Deformation

Double-reflective-layer structure disks with recording film containing a high-melting-point component that does not melt during recording are studied. Cr–Te is chosen for the high-melting-point component to be added to Ge–Sb–Te recording film to suppress a recording film material flow. A Si–Al double-reflective-layer structure has the advantage of increasing the material flow stopping power margin. The structure is also effective in preventing deformation of the recording marks due to the difference in light absorption between the crystallized region and the amorphized recording mark. A Si–Al double-reflective-layer-structure disk with Cr–Ge–Sb–Te recording film shows very little distortion in the reproduced signal waveform even after 104 overwrites of pulse-width modulation (PWM). This makes it suitable for high density recording as a rewritable digital video disk (DVD).