| 摘要 |
PURPOSE:To enhance a recording sensitivity and a reading accuracy, by a method wherein in a recording layer the composition ratio of GeSx and In is determined to be a specific ratio respectively in a 1/4 thick part from the substrate side and in a 1/4 thick part from the surface side. CONSTITUTION:As the materials for a recording layer, In and GeSx are used, but (x) is a number of 0<x<=2. In the recording layer, a 1/4 thick part from the substrate side has an In content lower than the other part of the recording layer and has a GeSx/In composition ratio more than 0.6 in an atom number ratio (Ge/In), and on the reverse side a 1/4 thick part from the surface side has a high In content and has a GeSx/In composition ratio ranging 0.6-0.2 in an atom number ratio (Ge/In). The recording layer is so constructed that the recording area composed with high reflectance and transmission is provided in a part close to the substrate and the recording area of low reflectance and transmission is provided close to the surface; in this manner, the contrast of signals is remarkably enhanced, thus raising a signal reading accuracy. |
