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10 January 2002 Simulation of recrystallization in phase-change recording materials
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Proceedings Volume 4342, Optical Data Storage 2001; (2002)
Event: Optical Data Storage, 2001, Santa Fe, NM, United States
Phase-change optical discs are common media for audio-visual equipment and computer peripherals. In such recording media as the DVD-RAM, amorphous marks are written on the crystalline matrix by controlling the power of laser beam pulses. Due to the need for higher capacity optical disc drives, track pitches are becoming narrower, so that the thermal effects of adjacent tracks are no longer negligible. This is also a problem in the track direction. Achieving higher density in drives requires smaller marks on the media, leading to shorter intervals between pulses. The thermal effects of the following pulses change the shape of the amorphous mark made by previous pulse. That is, the trailing boundary of an amorphous mark is re-crystallized by the heat of the following pulses. Close attention to the re-crystallization of the recording material is necessary to control the mark shapes on phase-change optical discs. We have simulated the movement of the crystalline/amorphous boundary during the writing process. We have also developed the concept of a 're-crystallization-ring' to explain the mark-forming process. The movement of the boundary was traced by drawing arrows to represent the crystallization direction and speed. The trace lines of these arrows matched the streamlines for crystal growth as observed by TEM. Simulation was done for both GeSbTe and Ag-InSbTe recording materials.
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Yoshiko Nishi, Hidehiko Kando, and Motoyasu Terao "Simulation of recrystallization in phase-change recording materials", Proc. SPIE 4342, Optical Data Storage 2001, (10 January 2002);

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