High performance phase change media for DVD-RAM

A rewritable digital versatile disk (DVD-RAM) has eight times more capacity than a CD-ROM disk, which makes it promising for use as a computer file memory device. Media compatibility is realized because a DVD-RAM uses the same write/read wavelength as the DVD-ROM, the same substrate thickness (the DVD-ROM disk uses a thin 0.6 mm-thick substrate so it can use a focusing lens with a large NA), and the same error correction method. The DVD-RAM uses phase-change recording media, so that rewriting by overwriting is easy, and reading and writing can be done with an optical head similar to that used for DVD-ROM. The authors demonstrate that 10/sup 5/ overwrites in mark edge recording and long storage life can be achieved on a new phase-change disk that has a double-reflective-layer structure and a recording film that contains a high-melting-point component.