Tokuhiko Handa

In-Ag-Te-Sb phase change recording media at compact disk linear velocity

The feasibility of In-Ag-Te-Sb phase change recording media was investigated at an actual compact disk (CD) linear velocity. The composition of 0.5 at% V-doped In3.8Ag12.4Te28.8Sb55.0 was used for the recording layer which we have reported previously. To improve the repetition property of overwriting, the disk structure was modified so that the cooling rate of the disk was increased. Consequently, recording jitter of less than 30 ns and modulation of more than 60% were maintained up to 2000 repetitions of overwriting when eight-fourteen modulation (EFM) signal with pulse-train division was applied.

V and Ti Doping Effect on In-Ag-Te-Sb Optical Phase Change Rewritable Disc

In-Ag-Te-Sb is known as one of the alloys suitable for optical phase change recording, which has a high erasability at the linear recording velocity of around 7 m/s. The phase change rewritable recording succeeded at the linear recording velocity of 1.4 m/s with 0.5 at.% doping of Ti or V atoms, which delayed the crystallization time drastically, but maintained the high erasability. It was possible to make 103 repetition recordings with jitter in the reproduced signal of less than 40 ns, when the eight-fourteen modulation (EFM) signal, which is generally used for compact discs (CD), was applied.

Scanning Tunneling Microscopy Image of GeSb2Te4 Thin Films

A scanning tunneling microscopy image of thin film sputtered by a GeSb2Te4 target was obtained in oil conditions. The phase change of the films was confirmed from STM images when the films were heated at 250°C for 2 and 4 minutes. The arrangement of the atoms constituting the surface of the films was inferred through the consideration of the topographic image height with each different work function of the atoms.