부산대학교 도서관

The purpose of this study was to develop new active material for phase-change optical memory (Compact Disks) which would make it possible to record information with 3 or 4 levels of reflectivity and not only 2, as is the case now. With this goal in mind, the optical properties (reflectance) of Ge/sub 1/Sb/sub 2/Te/sub 4/ films doped with oxygen were investigated. X-ray diffraction shows that the crystalline phase for films with 2-8% oxygen corresponds to a Ge/sub 1/Sb/sub 2/Te/sub 4/ composition. However, the crystalline phase for films with more than 10% oxygen corresponds to Sb/sub 2/Te/sub 3/. This phase segregation in films containing more than 10% oxygen gives, as a result, an increase in nucleation times and in laser-induced crystallization times, making multilevel recording possible, that is to say, optical memory with ternary or quaternary code instead of just binary code.